What Is a Sibling Anyway? Full, Half, Three-Quarters, Step, Adopted, Donor-Conceived & Twins

I’ve seen the term sibling used many different ways, sometimes incorrectly.

When referring to their own siblings, people usually use the term brother or sister, regardless of whether they are talking about a full, half or step-sibling. It’s a term of heart or description. It’s often genealogists who are focused on which type of sibling. As far as I’m concerned, my brother is my brother, regardless of which type of brother. But in terms of genetics, and genealogy, there’s a huge difference. How we feel about our sibling(s) and how we are biologically related are two different things.

Let’s cover the various types of siblingship and how to determine which type is which.

  • Full Siblings – Share both parents
  • Half-Siblings – Share only one parent
  • Three-Quarter Siblings – It’s complicated
  • Adopted Siblings
  • Donor-Conceived
  • Step-Siblings – Share no biological parent
  • Twins – Fraternal and Identical

Full Siblings

Full siblings share both parents and share approximately 50% of their DNA with each other.

You can tell if you are full siblings with a match in various ways.

  1. You share the same fairly close matches on both parents’ sides. For example, aunts or uncles or their descendants.

Why do I say close matches? You could share one parent and another more distant relative on the other parent’s side. Matching with close relatives like aunts, uncles or first cousins at the appropriate level is an excellent indicator unless your parents or grandparents are available for testing. If you are comparing to grandparents, be sure to confirm matches to BOTH grandparents on each side.

  1. Full siblings will share in the ballpark of 2600 cM, according to DNAPainter’s Shared cM Tool.

Keep in mind that you can share more or less DNA, hence the range. It’s also worth noting that some people who reported themselves as full siblings in the Shared cM project were probably half siblings and didn’t realize it.

  1. Full siblings will share a significant amount of fully identical regions (FIR) of DNA with each other, meaning they share DNA at the same DNA address from both parents, as illustrated above. Shared DNA with each other inherited from Mom and Dad are blocked in green. The fully identical regions, shared with both parents, are bracketed in purple. You can’t make this determination at FamilyTreeDNA, MyHeritage or Ancestry, but you can at both 23andMe and GEDmatch.

At GEDmatch, the large fully green areas in the chromosome browser “graphics and positions” display indicates full siblings, where DNA is shared from both parents at that location.

I wrote about the details of how to view fully identical regions (FIR) versus half identical regions (HIR) in the article, DNA: In Search of…Full and Half-Siblings.

  1. If your parents/grandparents have tested, you and your full sibling will both match both parents/grandparents. Yes, I know this sounds intuitive, but sometimes it’s easy to miss the obvious.

At FamilyTreeDNA, you can use the matrix tool to see who matches each other in a group of people that you can select. In this case, both siblings are compared to the father, but if the father isn’t available, a close paternal relative could substitute. Remember that all people who are 2nd cousins or closer will match.

  1. At Ancestry, full siblings will be identified as either “brother” or “sister,” while half-siblings do not indicate siblingship. Half-siblings are called “close family” and a range of possible relationships is given. Yes, Ancestry, is looking under the hood at FIR/HIR regions. I have never seen a full sibling misidentified as anything else at Ancestry. Unfortunately, Ancestry does not give customers access to their matching chromosome segment location data.
  2. Y-DNA of males who are full siblings will match but may have some slight differences. Y-DNA alone cannot prove a specific relationship, with very rare exceptions, but can easily disprove a relationship if two males do not match. Y-DNA should be used in conjunction with autosomal DNA for specific relationship prediction when Y-DNA matches.
  3. Y-DNA testing is available only through FamilyTreeDNA, but high-level haplogroup-only estimates are available through 23andMe. Widely divergent haplogroups, such as E versus R, can be considered a confirmed non-match. Different haplogroups within the same base haplogroup, such as R, but obtained from different vendors or different testing levels may still be a match if they test at the Big Y-700 level at FamilyTreeDNA.
  4. Mitochondrial DNA, inherited matrilineally from the mother, will match for full siblings (barring unusual mutations such as heteroplasmies) but cannot be used in relationship verification other than to confirm nonmatches. For both Y-DNA and mitochondrial DNA, it’s possible to have a lineage match that is not the result of a direct parental relationship.
  5. Mitochondrial DNA testing is available only through FamilyTreeDNA, but haplogroup-only estimates are included at 23andMe. Different base haplogroups such as H and J can be considered a non-match.
  6. A difference in ethnicity is NOT a reliable indicator of half versus full siblings.

Half-Siblings

Half-siblings share only one parent, but not both, and usually share about 25% of their DNA with each other.

You will share as much DNA with a half-sibling as you do some other close matches, so it’s not always possible for DNA testing companies to determine the exact relationship.

Referencing the MyHeritage cM Explainer tool, you can see that people who share 1700 cM of DNA could be related in several ways. I wrote about using the cM Explainer tool here.

Hints that you are only half-siblings include:

  1. At testing vendors, including Ancestry, a half-sibling will not be identified as a sibling but as another type of close match.
  2. If your parents or grandparents have tested, you will only match one parent or one set of grandparents or their descendants.
  3. You will not have shared matches on one parent’s side. If you know that specific, close relatives have tested on one parent’s side, and you don’t match them, but your other family members do, that’s a very big hint. Please note that you need more than one reference point, because it’s always possible that the other person has an unknown parentage situation.
  4. At 23andMe, you will not show fully identical regions (FIR).
  5. At GEDmatch, you will show only very minimal FIR.

Scattered, very small green FIR locations are normal based on random recombination. Long runs of green indicate that significant amounts of DNA was inherited from both parents. The example above is from half-siblings.

  1. At FamilyTreeDNA and 23andMe, most men who share a mother will also share an X chromosome match since men only inherit their X chromosome from their mother. However, it is possible for the mother to give one son her entire X chromosome from her father, and give the other son her entire X chromosome from her mother. Therefore, two men who do share a mother but don’t have an X chromosome match could still be siblings. The X is not an entirely reliable relationship predictor. However, if two men share an entire X chromosome match, it’s very likely that they are siblings on their mother’s side, or that their mothers are very close relatives.

Three-Quarter Siblings

This gets a little more complicated.

Three-quarter siblings occur when one parent is the same, and the other parents are siblings to each other.

Let’s use a real-life example.

A couple marries and has children. The mother dies, and the father marries the mother’s sister and has additional children. Those children are actually less than full siblings, but more than half-siblings.

Conversely, a woman has children by two brothers and those children are three-quarter siblings.

These were common situations in earlier times when a man needed a female companion to raise children and women needed a male companion to work on the farm. Neither one could perform both childcare and the chores necessary to earn a living in an agricultural society, and your deceased spouse’s family members were already people you knew. They already loved your children too.

Neither of these situations is historically unusual, but both are very difficult to determine using genetics alone, even in the current generation.

Neither X-DNA nor mitochondrial DNA will be helpful, and Y-DNA will generally not be either.

Unfortunately, three-quarter siblings’ autosomal DNA will fall in the range of both half and full siblings, although not at the bottom of the half-sibling range, nor at the top of the full sibling range – but that leaves a lot of middle ground.

I’ve found it almost impossible to prove this scenario without prior knowledge, and equally as impossible to determine which of multiple brothers is the father unless there is a very strong half-sibling match in addition.

The DNA-Sci blog discusses this phenomenon, but I can’t utilize comparison screenshots according to their terms of service.

Clearly, what we need are more known three-quarter siblings to submit data to be studied in order to (possibly) facilitate easier determination, probably based on the percentage frequency distribution of FIR/HIR segments. Regardless, it’s never going to be 100% without secondary genealogical information.

Three-quarter siblings aren’t very common today, but they do exist. If you suspect something of this nature, really need the answer, and have exhausted all other possibilities, I recommend engaging a very experienced genetic genealogist with experience in this type of situation. However, given the random nature of recombination in humans, we may never be able to confirm using any methodology, with one possible exception.

There’s one possibility using Y-DNA if the parents in question are two brothers. If one brother has a Y-DNA SNP mutation that the other does not have, and this can be verified by testing either the brothers who are father candidates or their other known sons via the Big Y-700 test – the father of the siblings could then be identified by this SNP mutation as well. Yes, it’s a long shot.

Three-quarter sibling situations are very challenging.

Step-siblings, on the other hand, are easy.

Step-Siblings

Step-siblings don’t share either parent, so their DNA will not match to each other unless their parents are somehow related to each other. Please note that this means either of their parents, not just the parents who marry each other.

One child’s parent marries the other child’s parent, resulting in a blended family. The children then become step-siblings to each other.

The terms step-sibling and half-sibling are often used interchangeably, and they are definitely NOT the same.

Adopted Siblings

Adopted siblings may not know they are adopted and believe, until DNA testing, that they are biological siblings.

Sometimes adopted siblings are either half-siblings or are otherwise related to each other but may not be related to either of their adoptive parents. Conversely, adopted siblings, one or both, may be related to one of their adoptive parents.

The same full and half-sibling relationship genetic clues apply to adopted siblings, as well as the tools and techniques in the In Search of Unknown Family series of articles.

Donor-Conceived Siblings

Donor-conceived siblings could be:

  • Half-siblings if the donor is the same father but a different mother.
  • Half-siblings if they share an egg donor but not a father.
  • Full siblings if they are full biological siblings to each other, meaning both donors are the same but not related to the woman into whom the fertilized egg was implanted, nor to her partner, their legal parents.
  • Not biologically related to each other or either legal parent.
  • Biologically related to one or both legal parents when a family member is either an egg or sperm donor.

Did I cover all of the possible scenarios? The essence is that we literally know nothing and should assume nothing.

I have known of situations where the brother (or brothers) of the father was the sperm donor, so the resulting child or children appear to be full or three-quarters siblings to each other. They are related to their legal father who is the mother’s partner. In other words, in this situation, the mother’s husband was infertile, and his brother(s) donated sperm resulting in multiple births. The children from this family who were conceived through different brothers and had very close (half-sibling) matches to their “uncles'” children were very confused until they spoke with their parents about their DNA results.

The same techniques to ascertain relationships would be used with donor-conceived situations. Additionally, if it appears that a biological relationship exists, but it’s not a full or half-sibling relationship, I recommend utilizing other techniques described in the In Search of Unknown Family series.

Twins or Multiple Birth Siblings

Two types of twin or multiple birth scenarios exist outside of assisted fertilization.

Fraternal twins – With fraternal or dizygotic twins, two eggs are fertilized independently by separate sperm. Just view this as one pregnancy with two siblings occupying the same space for the same 9 months of gestation. Fraternal twins can be male, female or one of each sex.

Fraternal twins are simply siblings that happen to gestate together and will match in the same way that full siblings match.

Please note that it’s possible for two of a woman’s eggs to be fertilized at different times during the same ovulation cycle, potentially by different men, resulting in twins who are actually half-siblings.

A difference in ethnicity is NOT a reliable indicator of fraternal or identical twins. Submitting your own DNA twice often results in slightly different ethnicity results.

Identical twins – Identical or monozygotic twins occur when one egg is fertilized by one sperm and then divides into multiple embryos that develop into different children. Those children are genetically identical since they were both developed from the same egg and sperm.

Two of the most famous identical twins are astronauts Mark and Scott Kelly.

Identical twins are the same sex and will look the same because they have the same DNA, except for epigenetic changes, but of course external factors such as haircuts, clothes and weight can make identical twins physically distinguishable from each other.

DNA testing companies will either identify identical twins as “self,” “identical twin” or “parent/child” due to the highest possible shared cM count plus fully matching FIR regions.

For identical twins, checking the FIR versus HIR is a positive identification as indicated above at GEDmatch with completely solid green FIR regions. Do not assume twins that look alike are identical twins.

Siblings

Whoever thought there would be so many kinds of siblings!

If you observe the need to educate about either sibling terminology or DNA identification methodologies, feel free to share this article. When identifying relationships, never assume anything, and verify everything through multiple avenues.

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X Chromosome Master Class

The X chromosome can be especially useful to genetic genealogists because it has a unique inheritance path. Thanks to that characteristic, some of the work of identifying your common ancestor is done just by simply HAVING an X match.

Unfortunately, X-DNA and X matching is both underutilized and somewhat misunderstood – in part because not all vendors utilize the X chromosome for matching.

The X chromosome has the capability of reaching further back in time and breaking down brick walls that might fall no other way.

Hopefully, you will read this article, follow along with your own DNA results and make important discoveries.

Let’s get started!

Who Uses the X Chromosome?

The X chromosome is autosomal in nature, meaning it recombines under some circumstances, but you only inherit your X chromosome from certain ancestors.

It’s important to understand why, and how to utilize the X chromosome for matching. In this article, I’ve presented this information in a variety of ways, including case studies, because people learn differently.

Of the four major testing vendors, only two provide X-DNA match results.

  • FamilyTreeDNA – provides X chromosome results and advanced matching capabilities including filtered X matching
  • 23andMe – provides X chromosome results, but not filtered X matching without downloading your results in spreadsheet format
  • Ancestry and MyHeritage do not provide X-DNA results but do include the X in your raw DNA file so you can upload to vendors who do provide X matching
  • GEDmatch – not a DNA testing vendor but a third-party matching database that provides X matching in addition to other tools

It’s worth noting at this point that X-DNA and mitochondrial DNA is not the same thing. I wrote about that, here. The source of this confusion is that the X chromosome and mitochondrial DNA are both associated in some way with descent from females – but they are very different and so is their inheritance path.

So, what is X-DNA and how does it work?

What is X-DNA?

Everyone inherits two copies of each of chromosomes 1-22, one copy of each chromosome from each of your parents.

That’s why DNA matching works and each match can be identified as “maternal” or “paternal,” depending on how your match is related to you. Each valid match (excluding identical by chance matches) will be related either maternally, or paternally, or sometimes, both.

Your 23rd chromosome is your sex determination chromosome and is inherited differently. Chromosome 23 is comprised of X and Y DNA.

Everyone inherits one copy of chromosome 23 from each parent.

  • Males inherit a Y chromosome from their father, which is what makes males male. They do not inherit an X chromosome from their father.
  • Males always inherit an X chromosome from their mother.
  • Females inherit an X chromosome from both parents, which is what makes them female. Females have two X chromosomes, and no Y chromosome.
Chromosome 23 Father Contributes Mother Contributes
Male Child Y chromosome X chromosome
Female Child X chromosome X chromosome

X-DNA and mitochondrial DNA are often confused, but they are not the same thing. In fact, they are completely different.

Mitochondrial DNA, in BOTH males and females is always inherited from only the mother and only descends from the direct matrilineal line, so only the mother’s mother’s mother’s direct line. X DNA can be inherited from a number of ancestors based on a specific inheritance path.

Everyone has both X-DNA AND mitochondrial DNA.

Because males don’t inherit an X chromosome from their father, X chromosome matching has a unique and specific pattern of descent which allows testers who match to immediately eliminate some potential common ancestors.

  • Males only inherit an X chromosome from their mother, which means they can only have legitimate X matches on their mother’s side of their tree.
  • Females, on the other hand, inherit an X chromosome from both their mother and father. Their father only has one X chromosome to contribute, so his daughter receives her paternal grandmother’s X chromosome intact.
  • Both males and females inherit their mother’s X chromosome just like any of the other 22 autosomes. I wrote about chromosomes, here.

However, the unique X chromosome inheritance path provides us with a fourth very useful type of DNA for genealogy, in addition to Y-DNA, mitochondrial and autosomal DNA.

For the vendors who provide X-matching, it’s included with your autosomal test and does not need to be purchased separately.

The Unique X Chromosome

The X chromosome, even though it is autosomal in nature, meaning it does recombine and divide in certain circumstances, is really its own distinct tool that is not equivalent to autosomal matching in the way we’re accustomed. We just need to learn about the message it’s delivering and how to interpret X matches.

FamilyTreeDNA is one of two vendors who utilizes X chromosome matching, along with 23andMe, which is another good reason to encourage your matches at other vendors to upload their DNA file to FamilyTreeDNA for free matching.

The four major vendors do include X-DNA results in their raw DNA download file, even if they don’t provide X-matching themselves. This means you can upload the results to either FamilyTreeDNA or GEDmatch where you can obtain X matches. I provided step-by-step download/upload instructions for each vendor here.

Let’s look how X matching is both different, and beneficial.

My X Chromosome Family Tree

We are going to build a simple case study. A case study truly is worth 1000 descriptions.

This fan chart of my family tree colorizes the X chromosome inheritance path. In this chart, males are colored blue and females pink, but the salient point is that I can inherit some portion of (or all of) a copy of my X chromosome from the colorized ancestors, and only those ancestors.

Because males don’t inherit an X chromosome from their father, they CANNOT inherit any portion of an X chromosome from their father’s ancestors.

Looking at my father’s half of the chart, at left, you see that I inherited an X chromosome from both of my parents, but my father only inherited an X chromosome from his mother, Ollie Bolton. His father’s portion of the tree is uncolored, so no X chromosome could have descended from his paternal ancestors to him. Therefore he could not pass any X chromosome segments to me from his paternal side – because he doesn’t have X DNA from his father.

Hence, I didn’t inherit an X chromosome from any of the people whose positions in the chart are uncolored, meaning I can only inherit an X chromosome from the pink or blue people.

Essentially any generational male to male, meaning father/son relationship is an X-DNA blocker.

I know positively that I inherited my paternal grandmother, Ollie Bolton’s entire X chromosome, because hers is the only X chromosome my father, in the fan chart above, had to give me. His entire paternal side of the fan chart is uncolored.

Men only ever inherit their X chromosome from their mother. The only exception to this is if a male has the rare genetic condition of Klinefelter Syndrome, also known as XXY. If you are an adult male, it’s likely that you’ll already know if you have Klinefelters, so that’s probably the last possibility you should consider if you appear to have paternal X matches, not the first.

Sometimes, men appear to have X matches on their father’s side, but (barring Klinefelter’s) this is impossible. Those matches must either be identical by chance, or somehow related in an unknown way on their mother’s side.

Everyone inherits an X chromosome from their mother that is some combination of the X from her father and mother. It’s possible to inherit all of your maternal grandmother or maternal grandfather’s X chromosome, meaning they did not recombine during meiosis.

Using DNA Painter as an X Tool

I use DNAPainter to track my matches and correlate segments with ancestors.

I paint my DNA segments for all my chromosomes at DNAPainter which provides me with a central tracking mechanism that is visual in nature and allows me to combine matches from multiple vendors who provide segment information. I provide step-by-step instructions for using DNAPainter, here.

This is my maternal X chromosome with my matches painted. I’ve omitted my matches’ names for privacy.

On the left side of the shaded grey column, those matches are from my maternal grandmother’s ancestors. On the right side, those matches are from my maternal grandfather’s ancestors.

The person in the grey column descends from unknown ancestors. In other words, I can tell that they descend from my maternal line, but I can’t (yet) determine through which of my two maternal grandparents.

There’s also an area to the right of the grey column where there are no matches painted, so I don’t know yet whether I inherited this portion of my X chromosome from my maternal grandmother or maternal grandfather.

The small darker pink columnar band is simply marking the centromere of the chromosome and does not concern us for this discussion.

Click on any image to enlarge

In this summary view of my paternal X chromosome, above, it appears that I may well have inherited my entire X chromosome from my paternal great-grandmother. We know, based on our inheritance rules that I clearly received my paternal grandmother’s X chromosome, because that’s all my father had to give me.

However, by painting my matches based on their ancestors, and selecting the summary view, you can see that most of my paternal X chromosome can be accounted for, with the exception of rather small regions with the red arrows.

It’s not terribly unusual for either a male or female to inherit their entire maternal X chromosome from one grandparent, or in this case, great-grandparent.

Of course, a male doesn’t inherit an X chromosome from their father, but a female can inherit her paternal X chromosome from either or both paternal grandparents.

Does Size Matter?

Generally speaking, an X match needs to be larger than a match on the other chromosomes to be considered genealogically equivalent in the same timeframe as other autosomal matches. This is due to:

  • The unique inheritance pattern, meaning fewer recombination events occurred.
  • The fact that X-DNA is NOT inherited from several lines.
  • The X chromosome has lower SNP density, meaning it contains fewer SNPs, so there are fewer possible locations to match when compared to the other chromosomes.

I know this equivalency requirement sounds negative, but it’s actually not. It means 7 cM (centimorgans) of DNA on the X chromosome will reach back further in time, so you may carry the DNA of an ancestor on the X chromosome that you no longer carry on other chromosomes. It may also mean that older segments remain larger. It’s actually a golden opportunity.

It sounds much more positive to say that a 16 cM X match for a female, or a 13 cM X match for a male is about the same as a 7 cM match for any other autosomal match in the same generation.

Of course, if the 7 cM match gets divided in the following generation, it has slipped below the matching threshold. If a 16 or 13 cM X match gets divided, it’s still a match. Plus, in some generations, if passed from father to daughter, it’s not divided or recombined. So a 7 cM X match may well be descended from ancestors further back in time.

X Chromosome Differences are Important!

Working with our great-great grandparent’s generation, we have 16 direct ancestors as illustrated in the earlier fan chart.

Given that females inherit from 8 X-chromosome ancestors in total, they are going to inherit an average of 45.25 cM of X-DNA from each of those ancestors. Females have two X chromosomes for a total length of 362 cM of X-DNA from both parents.

A male only has one X chromosome, 181 cM in length, so he will receive an average of 36.2 cM from each of 5 ancestors, and it’s all from his mother’s side.

In this chart, I’ve shown the total number of cMs for all of the autosomes, meaning chromosomes 1-22 and, separately, the X for males and females.

  • The average total cM for chromosomes 1-22 individually is 304 cM. (Yes, each chromosome is a different length, but that doesn’t matter for averages.)
  • That 304 cM can be inherited from any of 16 ancestors (in your great-grandparent’s generation)
  • The total number of cM on the X chromosomes for both parents for females totals 362
  • The total cM of X-DNA for males is 181 cM
  • The calculated average cM inherited for the X chromosome in the same generation is significantly different, shown in the bottom row.

The actual average for males and females for any ancestor on any random non-X chromosome (in the gg-grandparent generation) is still 19 cM. Due to the inheritance pattern of the X chromosome, the female X-chromosome average inheritance is 45.25 cM and the male average is 36.2 cM, significantly higher than the average of 19 cM that genetic genealogists have come to expect at this relationship distance on the other chromosomes, combined.

How Do I Interpret an X Match?

It’s important to remember when looking at X matching that you’re only looking at the amount of DNA from one chromosome. When you’re looking at any other matching amount, you’re looking at a total match across all chromosomes, as reported by that vendor. Vendors report total matching DNA differently.

  • The total amount of matching autosomal DNA does not include the X chromosome cMs at FamilyTreeDNA. X-DNA matching cMs are reported separately.
  • The total amount of matching autosomal DNA does include the X chromosome cMs in the total cM match at 23andMe
  • X-DNA is not used for matching or included in the match amount at either MyHeritage or Ancestry, but is included in the raw DNA data download files for all four vendors.
  • The total match amount shows the total for 22 (or 23) chromosomes, NOT just the X chromosome(s). That’s not apples to apples.

Therefore, an X match of 45 cM for a female or 36 for a male is NOT (necessarily) equivalent to a 19 cM non-X match. That 19 cM is the total for 22 chromosomes, while the X match amount is just for one chromosome.

You might consider a 20 cM match on the regular autosomes significant, but a 20 cM X-only match *could* be only roughly equivalent to a 10ish cM match on chromosomes 1-22 in the same generation. That’s the dog-leg inheritance pattern at work.

This is why FamilyTreeDNA does not report an X-only match if there is no other autosomal match. A 19 cM X match is not equivalent to a 19cM match on chromosomes 1-22. Not to mention, calculating relationships based on cM ranges becomes more difficult when the X is included.

However, the flip side is that because of the inheritance pattern of the X chromosome, that 19 cM match, if valid and not IBC, may well reach significantly further back in time than a regular autosomal matches. This can be particularly important for people seeking either Native or enslaved African ancestors for whom traditional records are elusive if they exist at all.

Critical Take-Away Messages

Here are the critical take-away messages:

  1. Because there are fewer ancestral lineages contributing to the tester’s X chromosome, the amount of X chromosomal DNA that a tester inherits from the ancestors who contribute to their X chromosome is increased substantially.
  2. The DNA of the contributing ancestors is more likely to be inherited, because there are fewer other possible contributing ancestors, meaning fewer recombination events or DNA divisions/recombinations.
  3. X-DNA is also more likely to be inherited because when passed from mother to son, it’s passed intact and not admixed with the DNA of the father.
  4. X matches cannot be compared equally to either percentages or cM amounts on any of the other chromosomes, or autosomal DNA in total, because X matching only reports the amount on one single chromosome, while your total cM match amount reports the amount of DNA that matches from all chromosomes (which includes the X at 23andMe).
  5. If you have X matches at 23andMe and/or FamilyTreeDNA, you can expect your total matching to be higher at 23andMe because they include the X matching cM in the total amount of shared DNA. FamilyTreeDNA provides the amount of X matching DNA separately, but not included in the total. MyHeritage and Ancestry do not include X matching DNA.

For clarity, at FamilyTreeDNA, you can see my shared DNA match with my mother. Of course, I match her on the total length of all my chromosomes, which is 3563 cM, the total Shared DNA for chromosomes 1-22. This includes all chromosomes except for the X chromosome which is reported separately at 181 cM. The longest contiguous block of shared DNA is 284 cM, the entire length of chromosome 1, the longest chromosome.

Because I’m a female, I match both parents on the full length of all 23 chromosomes, including 181 cM on both X chromosomes, respectively. Males will only match their mother on their X chromosome, meaning their total autosomal DNA match to their father, because the X is excluded, is 181 cM less than to their mother.

This difference in the amount of shared DNA with each parent, plus the differences in how DNA totals are reported by various vendors is also challenging for tools like DNAPainter’s Shared cM Tool which is based on the crowd sourced Shared cM Project that averages shared DNA numbers for known relationships at various vendors and translates those numbers into possible relationships for unknown matches.

Not all vendors report their total amount of shared DNA the same way. This is true for both X-DNA and half identical (HIR) versus fully identical (FIR) segments at 23andMe. This isn’t to say either approach is right or wrong, just to alert you to the differences.

Said Another Way

Let’s look at this another way.

If the average on any individual chromosome is 19 cMs for a relationship that’s 5 generations back in time. The average X-DNA for the same distance relationship is substantially more, which means that:

  • The X-DNA probably reaches further back in time than an equivalent relationship on any other autosome.
  • The X-DNA will have (probably) divided fewer times, and more DNA will descend from individual ancestors.
  • The inheritance path, meaning potential ancestors who contributed the X chromosomal DNA, is reduced significantly.

It’s challenging to draw equivalences when comparing X-DNA matching to the other chromosomes due to several variables that make interpretation difficult.

Based on the X-match size in comparison to the expected 19 cM single chromosome match at this genealogical distance, what is the comparable X-DNA segment size to the minimum 7 cM size generally accepted as valid on other chromosomes? What would be equal to a 7 cM segment on any other single random autosomal match, even though we know the inheritance probabilities are different and this isn’t apples to apples? Let’s pretend that it is.

This calculation presumes at the great-great-grandparent level that the 19 cM is in one single segment on a single chromosome. Now let’s divide 19 cM by 7 cM, which is 2.7, then divide the X amounts by the same number for the 7 cM equivalent of 16.75 cM for a female and 13.4 cM for a male.

When people say that you need a “larger X match to be equivalent to a regular autosomal match,” this is the phenomenon being referenced. Clearly a 7 cM X match is less relevant, meaning not equivalent, in the same generation as a 7 cM regular autosomal match.

Still, X matching compared to match amounts shown on the other chromosomes is never exact;u apples to apples because:

  • You’re comparing one X chromosome to the combined DNA amounts of many chromosomes.
  • The limited recombination path.
  • DNA from the other autosomes is less likely to be inherited from a specific ancestor.
  • The X chromosome has a lower SNP density than the other chromosomes, meaning fewer SNPs per cM.
  • The X-DNA may well reach further back in time because it has been divided less frequently.

Bottom Line

The X chromosome is different and holds clues that the other autosomes can’t provide.

Don’t dismiss X matches even if you can’t identify a common ancestor. Given the inheritance path, and the reduced number of divisions, your X-DNA may descend from an ancestor further back in time. I certainly would NOT dismiss X matches with smaller cMs than the 13 and 16 shown above, even though they are considered “equivalent” in the same generation.

X chromosome matching can’t really be equated to matching on the other chromosomes. They are two distinct tools, so they can’t be interpreted identically.

Different vendors treat the X chromosome differently, making comparison challenging.

  • 23andMe includes not only the X chromosome in their cM total, but doubles the Fully Identical Regions (FIR) when people, such as full siblings, share the same DNA from both parents. I wrote about that here.
  • Ancestry does not include the X in their cM match calculations.
  • Neither does MyHeritage.
  • FamilyTreeDNA shows an X match only when it’s accompanied by a match on another chromosome.

The Shared cM Project provides an average of all of the data input by crowdsourcing from all vendors, by relationship, which means that the cM values for some relationships are elevated when compared to the same relationship or even same match were it to be reported from a different vendor.

The Best Part!

The X chromosome inheritance pattern means that you’re much more likely to carry some amount of a contributing ancestor’s X-DNA than on any other chromosome.

  • X-DNA may well be “older” because it’s not nearly as likely to be divided, given that there are fewer opportunities for recombination.
  • When you’re tracking your X-DNA back in your tree, whenever you hit a male, you get an automatic “bump” back a generation to his mother. It’s like the free bingo X-DNA square!
  • You can immediately eliminate many ancestors as your most recent common ancestor (MRCA) with an X-DNA match.
  • Because X-DNA reaches further back in time, sometimes you match people who descend from common ancestors further back in time as well.

If you match someone on multiple segments, if one of those matching segments is X-DNA, that segment is more likely to descend from a different ancestor than the segments on chromosomes 1-22. I’ve found many instances where an X match descends from a different ancestor than matching DNA segments on the autosomes. Always evaluate X matches carefully.

Sometimes X-DNA is exactly what you need to solve a mystery.

Ok, now let’s step through how to use X-DNA in a real-life example.

Using X DNA to Solve a Mystery

Let’s say that I have a 30 cM X match with a male.

  • I know immediately that our most recent common ancestor (MRCA) is on HIS mother’s side.
  • I know, based on my fan chart, which ancestral lines are eliminated in my tree. I’ve immediately narrowed the ancestors from 16 to 5 on his side and 16 to 8 on my side.
  • Two matching males is even easier, because you know immediately that the common ancestor must be on both of their mother’s sides, with only 5 candidate lines each at the great-great-grandparent generation.

Female to female matches are slightly more complex, but there are still several immediately eliminated lines each. That means you’ve already eliminated roughly half of the possible relationships by matching another female on their X chromosome.

In this match with a female second cousin, I was able to identify who she was via our common ancestor based on the X chromosome path. In this chart, I’m showing the relevant halves of her chart at left (paternal), and mine (maternal), side by side.

I added blockers on her chart and mine too.

As it turns out, we both inherited most of our X chromosome from our great-grandparents, marked above with the black stars.

Several lines are blocked, and my grandfather’s X chromosome is not a possibility because the common ancestor is my maternal grandmother’s parents. My grandfather is not one of her ancestors.

Having identified this match as my closest relative (other than my mother) to descend on my mother’s maternal side, I was able to map that portion of my X chromosome to my great-grandparents Nora Kirsch and Curtis Benjamin Lore.

My X Chromosome at DNA Painter

Here’s my maternal X chromosome at DNAPainter and how I utilized chromosome painting to push the identification of the ancestors whose X chromosome I inherited back an additional two generations.

Using that initial X chromosome match with my second cousin, shown by the arrow at bottom of the graphic, I mapped a large segment of my maternal X chromosome to my maternal great-grandparents.

By viewing the trees of subsequent X maternal matches, I was then able to push those common segments, shown painted directly above that match with the same color, back another two generations, to Joseph Hill, born in 1790, and Nabby Hall. I was able to do that based on the fact that other matches descend from Joseph and Nabby through different children, meaning we all triangulate on that common segment. I wrote about triangulation at DNAPainter, here.

I received no known X-DNA from my great-grandmother, Nora Kirsch, although a small portion of my X chromosome is still unassigned in yellow as “Uncertain.”

I received a small portion of my maternal X chromosome, in magenta, at left, from my maternal great-great-grandparents, John David Miller and Margaret Lentz.

The X chromosome is a powerful tool and can reach far back in time.

In some cases, the X, and other chromosomes can be inherited intact from one grandparent. I could have inherited my mother’s entire copy of her mother’s, or her father’s X chromosome based on random recombination, or not. As it turns out, I didn’t, and I know that because I’ve mapped my chromosomes to identify my ancestors based on common ancestors with my matches.

X-DNA Advanced Matches at FamilyTreeDNA

At FamilyTreeDNA, the Advanced Matches tab includes the ability to search for X matches, either within the entire database, or within specific projects. I find the project selection to be particularly useful.

For example, within the Claxton project, my father’s maternal grandmother’s line, I recognize my match, Joy, which provides me an important clue as to the possible common ancestor(s) of our shared segments.

Joy’s tree shows that her 4-times great-grandparents are my 3-times great-grandparents, meaning we are 4th cousins once removed and share 17 cM of DNA on our X chromosome across two segments.

Don’t be deceived by the physical appearance of “size” on your chromosomes. The first segment that spans the centromere, or “waist” of the chromosome, above, is 10.29 cM, and the smaller segment at right is 7.02 cM. SNPs are not necessarily evenly distributed along chromosomes.

Remember, an X or other autosomal match doesn’t necessarily mean the entire match is contained in one segment so long as it’s large enough to be divided in two parts and survive the match threshold.

It’s worth noting that Joy and I actually share at least two different, unrelated ancestral lines, so I need to look at Joy’s blocked lines to see if one of those common ancestral lines is not a possibility for our X match. It’s important to evaluate all possible ancestors, plus the inheritance path to eliminate any lineage that involves a father to son inheritance on the X chromosome.

Last but not least, you may match on your X chromosome through a different ancestor than on other chromosomes. Every matching segment has its own individual history. It’s not safe to assume.

Now, take a look at your X chromosome matches at FamilyTreeDNA, 23andMe, and GedMatch. What will you discover?

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DNA: In Search of…Full and Half-Siblings

This is the fifth article in our series of articles about searching for unknown close family members, specifically; parents, grandparents, or siblings. However, these same techniques can be applied by genealogists to identify ancestors further back in time as well.

Please note that if a family member has tested and you do NOT see their results, ask them to verify that they have chosen to allow matching and for other people to view them in their match list. That process varies at different vendors.

You can also ask if they can see you in their results.

All Parties Need to Test

Searching for unknown siblings isn’t exactly searching, because to find them, they, themselves, or their descendant(s) must have taken a DNA test at the same vendor where you tested or uploaded a DNA file.

You may know through any variety of methods that they exist, or might exist, but if they don’t take a DNA test, you can’t find them using DNA. This might sound obvious, but I see people commenting and not realizing that the other sibling(s) must test too – and they may not have.

My first questions when someone comments in this vein are:

  1. Whether or not they are positive their sibling actually tested, meaning actually sent the test in to the vendor, and it was received by the testing company. You’d be surprised how many tests are living in permanent residence on someone’s countertop until it gets pushed into the drawer and forgotten about.
  2. If the person has confirmed that their sibling has results posted. They may have returned their test, but the results aren’t ready yet or there was a problem.
  3. AND that both people have authorized matching and sharing of results. Don’t hesitate to reach out to your vendor’s customer care if you need help with this.

Sibling Scenarios

The most common sibling scenarios are when one of two things happens:

  • A known sibling tests, only to discover that they don’t match you in the full sibling range, or not at all, when you expected they would
  • You discover a surprise match in the full or half-sibling range

Let’s talk about these scenarios and how to determine:

  • If someone is a sibling
  • If they are a full or half-sibling
  • If a half-sibling, if they descend from your mother or father

As with everything else genetic, we’ll be gathering and analyzing different pieces of evidence along the way.

Full and Half-Siblings

Just to make sure we are all on the same page:

  • A full sibling is someone who shares both parents with you.
  • A half-sibling is someone who shares one parent with you, but not the other parent.
  • A step-sibling is someone who shares no biological parents with you. This situation occurs when your parent marries their parent, after you are both born, and their parent becomes your step-parent. You share neither of your biological parents with a step-sibling, so you share no DNA and will not show up on each other’s match lists.
  • A three-quarters sibling is someone with whom you share one parent, but two siblings are the other parent. For example, you share the same mother, but one brother fathered you, and your father’s brother fathered your sibling. Yes, this can get very messy and is almost impossible for a non-professional to sort through, if even then. (This is not a solicitation. I do not take private clients.) We will not be addressing this situation specifically.

Caution

With any search for unknown relatives, you have no way of knowing what you will find.

In one’s mind, there are happy reunions, but you may experience something entirely different. Humans are human. Their stories are not always happy or rosy. They may have made mistakes they regret. Or they may have no regrets about anything.

Your sibling may not know about you or the situation under which you, or they, were born. Some women were victims of assault and violence, which is both humiliating and embarrassing. I wrote about difficult situations, here.

Your sibling or close family member may not be receptive to either you, your message, or even your existence. Just be prepared, because the seeking journey may not be pain-free for you or others, and may not culminate with or include happy reunions.

On the other hand, it may.

Please step back and ponder a bit about the journey you are about to undertake and the possible people that may be affected, and how. This box, once opened, cannot be closed again. Be sure you are prepared.

On the other hand, sometimes that box lid pops off, and the information simply falls in your lap one day when you open your match list, and you find yourself sitting there, in shock, staring at a match, trying to figure out what it all means.

Congratulations, You Have a Sibling!

This might not be exactly what runs through your mind when you see that you have a very close match that you weren’t expecting.

The first two things I recommend when making this sort of discovery, after a few deep breaths, a walk, and a cup of tea, are:

  • Viewing what the vendor says
  • Using the DNAPainter Shared cM Relationship Chart

Let’s start with DNAPainter.

DNAPainter

DNAPainter provides a relationship chart, here, based on the values from the Shared cM Project.

You can either enter a cM amount or a percentage of shared DNA. I prefer the cM amount, but it doesn’t really matter.

I’ll enter 2241 cM from a known half-sibling match. To enter a percent, click on the green “enter %.”

As you can see, statistically speaking, this person is slightly more likely to be a half-sibling than they are to be a full sibling. In reality, they could be either.

Looking at the chart below, DNAPainter highlights the possible relationships from the perspective of “Self.”

The average of all the self-reported relationships is shown, on top, so 2613 for a full sibling. The range is shown below, so 1613-3488 for a full sibling.

In this case, there are several possibilities for two people who share 2241 cM of DNA.

I happen to know that these two people are half-siblings, but if I didn’t, it would be impossible to tell from this information alone.

The cM range for full siblings is 1613-3488, and the cM range for half-siblings is 1160-2436.

  • The lower part of the matching range, from 1160-1613 cM is only found in half-siblings.
  • The portion of the range from 1613-2436 cM can be either half or full siblings.
  • The upper part of the range, from 2436-3488 cM is only found in full siblings.

If your results fall into the center portion of the range, you’re going to need to utilize other tools. Fortunately, we have several.

If you’ve discovered something unexpected, you’ll want to verify using these tools, regardless. Use every tool available. Ranges are not foolproof, and the upper and lower 10% of the responses were removed as outliers. You can read more about the shared cM Project, here and here.

Furthermore, people may be reporting some half-sibling relationships as full sibling relationships, because they don’t expect to be half-siblings, so the ranges may be somewhat “off.”

Relationship Probability Calculator

Third-party matching database, GEDmatch, provides a Relationship Probability Calculator tool that is based on statistical probability methods without compiled user input. Both tools are free, and while I haven’t compared every value, both seem to be reasonably accurate, although they do vary somewhat, especially at the outer ends of the ranges.

When dealing with sibling matches, if you are in all four databases, GEDmatch is a secondary resource, but I will include GEDmatch when they have a unique tool as well as in the summary table. Some of your matches may be willing to upload to GEDmatch if the vendor where you match doesn’t provide everything you need and GEDmatch has a supplemental offering.

Next, let’s look at what the vendors say about sibling matches.

Vendors

Each of the major vendors reports sibling relationships in a slightly different way.

Sibling Matches at Ancestry

Ancestry reports sibling relationships as Sister or Brother, but they don’t say half or full.

If you click on the cM portion of the link, you’ll see additional detail, below

Ancestry tells you that the possible relationships are 100% “Sibling.” The only way to discern the difference between full and half is by what’s next.

If the ONLY relationship shown is Sibling at 100%, that can be interpreted to mean this person is a full sibling, and that a half-sibling or other relationship is NOT a possibility.

Ancestry never stipulates full or half.

The following relationship is a half-sibling at Ancestry.

Ancestry identifies that possible range of relationships as “Close Family to First Cousin” because of the overlaps we saw in the DNAPainter chart.

Clicking through shows that there is a range of possible relationships, and Ancestry is 100% sure the relationship is one of those.

DNAPainter agrees with Ancestry except includes the full-sibling relationship as a possibility for 1826 cM.

Sibling Matches at 23andMe

23andMe does identify full versus half-siblings.

DNAPainter disagrees with 23andMe and claims that anyone who shares 46.2% of their DNA is a parent/child.

However, look at the fine print. 23andMe counts differently than any of the other vendors, and DNAPainter relies on the Shared cM Project, which relies on testers entering known relationship matching information. Therefore, at any other vendor, DNAPainter is probably exactly right.

Before we understand how 23andMe counts, we need to understand about half versus fully identical segments.

To determine half or full siblings, 23andMe compares two things:

  1. The amount of shared matching DNA between two people
  2. Fully Identical Regions (FIR) of DNA compared to Half Identical Regions (HIR) of DNA to determine if any of your DNA is fully identical, meaning some pieces of you and your sibling’s DNA is exactly the same on both your maternal and paternal chromosomes.

Here’s an example on any chromosome – I’ve randomly selected chromosome 12. Which chromosome doesn’t matter, except for the X, which is different.

Your match isn’t broken out by maternal and paternal sides. You would simply see, on the chromosome browser, that you and your sibling match at these locations, above.

In reality, though, you have two copies of each chromosome, one from Mom and one from Dad, and so does your sibling.

In this example, Mom’s chromosome is visualized on top, and Dad’s is on the bottom, below, but as a tester, you don’t know that. All you know is that you match your sibling on all of those blue areas, above.

However, what’s actually happening in this example is that you are matching your sibling on parts of your mother’s chromosome and parts of your father’s chromosome, shown above as green areas

23andMe looks at both copies of your chromosome, the one you inherited from Mom, on top, and Dad, on the bottom, to see if you match your sibling on BOTH your mother’s and your father’s chromosomes in that location.

I’ve boxed the green matching areas in purple where you match your sibling fully, on both parents’ chromosomes.

If you and your sibling share both parents, you will share significant amounts of the same DNA on both copies of the same chromosomes, meaning maternal and paternal. In other words, full siblings share some purple fully identical regions (FIR) of DNA with each other, while half-siblings do not (unless they are also otherwise related) because half-siblings only share one parent with each other. Their DNA can’t be fully identical because they have a different parent that contributed the other copy of their chromosome.

Total Shared DNA Fully Identical DNA from Both Parents
Full Siblings ~50% ~25%
Half Siblings ~25% 0
  • Full siblings are expected to share about 50% of the same DNA. In other words, their DNA will match at that location. That’s all the green boxed locations, above.
  • Full siblings are expected to share about 25% of the same DNA from BOTH parents at the same location on BOTH copies of their chromosomes. These are fully identical regions and are boxed in purple, above.

You’ll find fully identical segments about 25% of the time in full siblings, but you won’t find fully identical segments in half-siblings. Please note that there are exceptions for ¾ siblings and endogamous populations.

You can view each match at 23andMe to see if you have any completely identical regions, shown in dark purple in the top comparison of full siblings. Half siblings are shown in the second example, with less total matching DNA and no FIR or completely identical regions.

Please note that your matching amount of DNA will probably be higher at 23andMe than at other companies because:

  • 23andMe includes the X chromosome in the match totals
  • 23andMe counts fully identical matching regions twice. For full siblings, that’s an additional 25%

Therefore, a full sibling with an X match will have a higher total cM at 23andMe than the same siblings elsewhere because not only is the X added into the total, the FIR match region is added a second time too.

Fully Identical Regions (FIR) and Half Identical Regions (HIR) at GEDmatch

At GEDMatch, you can compare two people to each other, with an option to display the matching information and a painted graphic for each chromosome that includes FIR and HIR.

If you need to know if you and a match share fully identical regions and you haven’t tested at 23andMe, you can both upload your DNA data file to GEDmatch and use their One to One Autosomal DNA Comparison.

On the following page, simply enter both kit numbers and accept the defaults, making sure you have selected one of the graphics options.

While GEDmatch doesn’t specifically tell you whether someone is a full or half sibling, you can garner additional information about the relationship based on the graphic at GEDmatch.

GEDMatch shows both half and fully identical regions.

The above match is between two full siblings using a 7 cM threshold. The blue on the bottom bar indicates a match of 7 cM or larger. Black means no match.

The green regions in the top bar indicate places where these two people carry the same DNA on both copies of their chromosome 1. This means that both people inherited the same DNA from BOTH parents on the green segments.

In the yellow regions, the siblings inherited the same DNA from ONE parent, but different DNA in that region from the other parent. They do match each other, just on one of their chromosomes, not both.

Without a tool like this to differentiate between HIR and FIR, you can’t tell if you’re matching someone on one copy of your chromosome, or on both copies.

In the areas marked with red on top, which corresponds to the black on the bottom band, these two siblings don’t match each other because they inherited different DNA from both parents in that region. The yellow in that region is too scattered to be significant.

Full siblings generally share a significant amount of FIR, or fully identical regions of DNA – about 25%.

Half siblings will share NO significant amount of FIR, although some will be FIR on very small, scattered green segments simply by chance, as you can see in the example, below.

This half-sibling match shares no segments large enough to be a match (7 cM) in the black section. In the blue matching section, only a few small green fragments of DNA match fully, which, based on the rest of that matching segment, must be identical by chance or misreads. There are no significant contiguous segments of fully identical DNA.

When dealing with full or half-siblings, you’re not interested in small, scattered segments of fully identical regions, like those green snippets on chromosome 6, but in large contiguous sections of matching DNA like the chromosome 1 example.

GEDmatch can help when you match when a vendor does not provide FIR/HIR information, and you need additional assistance.

Next, let’s look at full and half-siblings at FamilyTreeDNA

Sibling Matches at FamilyTreeDNA

FamilyTreeDNA does identify full siblings.

Relationships other than full siblings are indicated by a range. The two individuals below are both half-sibling matches to the tester.

The full range when mousing over the relationship ranges is shown below.

DNAPainter agrees except also gives full siblings as an option for the two half-siblings.

FamilyTreeDNA also tells you if you have an X match and the size of your X match.

We will talk about X matching in a minute, which, when dealing with sibling identification, can turn out to be very important.

Sibling Matches at MyHeritage

MyHeritage indicates brother or sister for full siblings

MyHeritage provides other “Estimated relationships” for matches too small to be full siblings.

DNAPainter’s chart agrees with this classification, except adds additional relationship possibilities.

Be sure to review all of the information provided by each vendor for close relationships.

View Close Known Relationships

The next easiest step to take is to compare your full or half-sibling match to known close family members from your maternal and paternal sides, respectively. The closer the family members, the better.

It’s often not possible to determine if someone is a half sibling or a full sibling by centiMorgans (cMs) alone, especially if you’re searching for unknown family members.

Let’s start with the simplest situation first.

Let’s say both of your parents have tested, and of course, you match both of them as parents.

Your new “very close match” is in the sibling range.

The first thing to do at each vendor is to utilize that vendor’s shared matches tool and see whether your new match matches one parent, or both.

Here’s an example.

Close Relationships at FamilyTreeDNA

This person has a full sibling match, but let’s say they don’t know who this is and wants to see if their new sibling matches one or both of their parents.

Select the match by checking the box to the left of the match name, then click on the little two-person icon at far right, which shows “In Common” matches

You can see on the resulting shared match list that both of the tester’s parents are shown on the shared match list.

Now let’s make this a little more difficult.

No Parents, No Problem

Let’s say neither of your parents has tested.

If you know who your family is and can identify your matches, you can see if the sibling you match matches other close relatives on both or either side of your family.

You’ll want to view shared matches with your closest known match on both sides of your tree, beginning with the closest first. Aunts, uncles, first cousins, etc.

You will match all of your family members through second cousins, and 90% of your third cousins. You can view additional relationship percentages in the article, How Much of Them is in You?.

I recommend, for this matching purpose, to utilize 2nd cousins and closer. That way you know for sure if you don’t share them as a match with your sibling, it’s because the sibling is not related on that side of the family, not because they simply don’t share any DNA due to their distance.

In this example, you have three sibling matches. Based on your and their matches to the same known first and second cousins, you can see that:

  • Sibling 1 is your full sibling, because you both match the same maternal and paternal first and second cousins
  • Sibling 2 is your paternal half-sibling because you both match paternal second cousins and closer, but not maternal cousins.
  • Sibling 3 is your maternal half-sibling because you both match maternal second cousins and closer, but not paternal cousins.

Close Relationships at Ancestry

Neither of my parents have tested, but my first cousin on my mother’s side has. Let’s say I have a suspected sibling or half-sibling match, so I click on the match’s name, then on Shared Matches.

Sure enough, my new match also matches my first cousin that I’ve labeled as “on my mother’s side.”

If my new match in the sibling range also matches my second cousins or closer on my father’s side, the new match is a full sibling, not a half-sibling.

Close Relationships at MyHeritage

Comparing my closest match provided a real surprise. I wonder if I’ve found a half-sibling to my mother.

Now, THIS is interesting.

Hmmm. More research is needed, beginning with the age of my match. MyHeritage provides ages if the MyHeritage member authorizes that information to be shared.

Close Relationships at 23andMe

Under DNA Relatives, click on your suspected sibling match, then scroll down and select “Find Relatives in Common.”

The Relatives in Common list shows people that match both of you.

The first common match is very close and a similar relationship to my closest match on my father’s side. This would be expected of a sibling. I have no common matches with this match to anyone on my mother’s side, so they are only related on my father’s side. Therefore they are a paternal half-sibling, not a full sibling.

More Tools Are Available

Hopefully, by now, you’ve been able to determine if your mystery match is a sibling, and if so, if they are a half or full sibling, and through which parent.

We have some additional tools that are relevant and can be very informative in some circumstances. I suggest utilizing these tools, even if you think you know the answer.

In this type of situation, there’s no such thing as too much information.

X Matching

X matching, or lack thereof, may help you determine how you are related to someone.

There are two types of autosomal DNA. The X chromosome versus chromosomes 1-22. The X chromosome (number 23) has a unique inheritance path that distinguishes it from your other chromosomes.

The X chromosome inheritance path also differs between men and women.

Here’s my pedigree chart in fan form, highlighting the ancestors who may have contributed a portion of their X chromosome to me. In the closest generation, this shows that I inherited an X chromosome from both of my parents, and who in each of their lines could have contributed an X to them.

The white or uncolored positions, meaning ancestors, cannot contribute any portion of an X chromosome to me based on how the X chromosome is inherited.

You’ll notice that my father inherited none of his X chromosome from any of his paternal ancestors, so of course, I can’t inherit what he didn’t inherit. There are a very limited number of ancestors on my father’s side whom I can inherit any portion of an X chromosome from.

Men receive their Y chromosome from their fathers, so men ONLY receive an X chromosome from their mother.

Therefore, men MUST pass their mother’s X chromosome on to their female offspring because they don’t have any other copy of the X chromosome to pass on.

Men pass no X chromosome to sons.

We don’t need to worry about a full fan chart when dealing with siblings and half-siblings.

We only need to be concerned with the testers plus one generation (parents) when utilizing the X chromosome in sibling situations.

These two female Disney Princesses, above, are full siblings, and both inherited an X chromosome from BOTH their mother and father. However, their father only has one X (red) chromosome to give them, so the two females MUST match on the entire red X chromosome from their father.

Their mother has two X chromosomes, green and black, to contribute – one from each of her parents.

The full siblings, Melody, and Cinderella:

  • May have inherited some portion of the same green and black X chromosomes from their mother, so they are partial matches on their mother’s X chromosome.
  • May have inherited the exact same full X chromosome from their mother (both inherited the entire green or both inherited the entire black), so they match fully on their mother’s X chromosome.
  • May have inherited the opposite X from different maternal grandparents. One inherited the entire green X and one inherited the entire black X, so they don’t match on their mother’s X chromosome.

Now, let’s look at Cinderella, who matches Henry.

This female and male full sibling match can’t share an X chromosome on the father’s side, because the male’s father doesn’t contribute an X chromosome to him. The son, Henry, inherited a Y chromosome instead from his father, which is what made them males.

Therefore, if a male and female match on the X chromosome, it MUST be through HIS mother, but could be through either of her parents. In a sibling situation, an X match between a male and female always indicates the mother.

In the example above, the two people share both of their mother’s X chromosomes, so are definitely (at least) maternally related. They could be full siblings, but we can’t determine that by the X chromosome in this situation, with males.

However, if the male matches the female on HER father’s X chromosome, there a different message, example below.

You can see that the male is related to the female on her father’s side, where she inherited the entire magenta X chromosome. The male inherited a portion of the magenta X chromosome from his mother, so these two people do have an X match. However, he matches on his mother’s side, and she matches on her father’s side, so that’s clearly not the same parent.

  • These people CAN NOT be full siblings because they don’t match on HER mother’s side too, which would also be his mother’s side if they were full siblings.
  • They cannot be maternal half-siblings because their X DNA only matches on her father’s side, but they wouldn’t know that unless she knew which side was which based on share matches.
  • They cannot be paternal half-siblings because he does not have an X chromosome from his father.

They could, however, be uncle/aunt-niece/nephew or first cousins on his mother’s side and her father’s side. (Yes, you’re definitely going to have to read this again if you ever need male-female X matching.)

Now, let’s look at X chromosome matching between two males. It’s a lot less complicated and much more succinct.

Neither male has inherited an X chromosome from their father, so if two males DO match on the X, it MUST be through their mother. In terms of siblings, this would mean they share the same mother.

However, there is one slight twist. In the above example, you can see that the men inherited a different proportion of the green and black X chromosomes from their common mother. However, it is possible that the mother could contribute her entire green X chromosome to one son, Justin in this example, and her entire black X chromosome to Henry.

Therefore, even though Henry and Justin DO share a mother, their X chromosome would NOT match in this scenario. This is rare but does occasionally happen.

Based on the above examples, the X chromosome may be relevant in the identification of full or half siblings based on the sexes of the two people who otherwise match at a level indicating a full or half-sibling relationship.

Here’s a summary chart for sibling X matching.

X Match Female Male
Female Will match on shared father’s full X chromosome, mother’s X is the same rules as chromosomes 1-22 Match through male’s mother, but either of female’s parents. If the X match is not through the female’s mother, they are not full siblings nor maternal half-siblings. They cannot have an X match through the male’s father. They are either full or half-siblings through their mother if they match on both of their mother’s side. If they match on his mother’s side, and her father’s side, they are not siblings but could be otherwise closely related.
Male Match through male’s mother, but either of female’s parents. If the X match is not through the female’s mother, they are not full siblings nor maternal half-siblings. They cannot have an X match through the male’s father. They are either full or half-siblings through their mother if they match on both or their mother’s side. If they match on his mother’s side, and her father’s side, they are not siblings but could be otherwise closely related. Both males are related on their mother’s side – either full or half-siblings.

Here’s the information presented in a different way.

DOES match X summary:

  • If a male DOES match a female on the X, he IS related to her through HIS mother’s side, but could match her on her mother or father’s side. If their match is not through her mother, then they are not full siblings nor maternal half-siblings. They cannot match through his father, so they cannot be paternal half-siblings.
  • If a female DOES match a female on the X, they could be related on either side and could be full or half-siblings.
  • If a male DOES match a male on the X, they ARE both related through their mother. They may also be related on their father’s side, but the X does not inform us of that.

Does NOT match X summary:

  • If a male does NOT match a female on the X, they are NOT related through HIS mother and are neither full siblings nor maternal half-siblings. Since a male does not have an X chromosome from his father, they cannot be paternal half-siblings based on an X match.
  • If a male does NOT match a male, they do NOT share a mother.
  • If a female does NOT match another female on the X, they are NOT full siblings and are NOT half-siblings on their paternal side. Their father only has one X chromosome, and he would have given the same X to both daughters.

Of the four autosomal vendors, only 23andMe and FamilyTreeDNA report X chromosome results and matching, although the other two vendors, MyHeritage and Ancestry, include the X in their DNA download file so you can find X matches with those files at either FamilyTreeDNA or GEDMatch if your match has or will upload their file to either of those vendors. I wrote step-by-step detailed download/upload instructions, here.

X Matching at FamilyTreeDNA

In this example from FamilyTreeDNA, the female tester has discovered two half-sibling matches, both through her father. In the first scenario, she matches a female on the full X chromosome (181 cM). She and her half-sibling MUST share their father’s entire X chromosome because he only had one X, from his mother, to contribute to both of his daughters.

In the second match to a male half-sibling, our female tester shares NO X match because her father did not contribute an X chromosome to his son.

If we didn’t know which parents these half-sibling matches were through, we can infer from the X matching alone that the male is probably NOT through the mother.

Then by comparing shared matches with each sibling, Advanced Matches, or viewing the match Matrix, we can determine if the siblings match each other and are from the same or different sides of the family.

Under Additional Tests and Tools, Advanced Matching, FamilyTreeDNA provides an additional tool that can show only X matches combined with relationships.

Of course, you’ll need to view shared matches to see which people match the mother and/or match the father.

To see who matches each other, you’ll need to use the Matrix tool.

At FamilyTreeDNA, the Matrix, located under Autosomal DNA Results and Tools, allows you to select your matches to see if they also match each other. If you have known half-siblings, or close relatives, this is another way to view relationships.

Here’s an example using my father and two paternal half-siblings. We can see that the half-siblings also match each other, so they are (at least) half-siblings on the paternal side too.

If they also matched my mother, we would be full siblings, of course.

Next, let’s use Y DNA and mitochondrial DNA.

Y DNA and Mitochondrial DNA

In addition to autosomal DNA, we can utilize Y DNA and mitochondrial DNA (mtDNA) in some cases to identify siblings or to narrow or eliminate relationship possibilities.

Given that Y DNA and mitochondrial DNA both have distinctive inheritance paths, full and half-siblings will, or will not, match under various circumstances.

Y DNA

Y DNA is passed intact from father to son, meaning it’s not admixed with any of the mother’s DNA. Daughters do not inherit Y DNA from their father, so Y DNA is only useful for male-to-male comparisons.

Two types of Y DNA are used for genealogy, STR markers for matching, and haplogroups, and both are equally powerful in slightly different ways.

Y DNA at FamilyTreeDNA

Men can order either 37 or 111 STR marker tests, or the BIg Y which provides more than 700 markers and more. FamilyTreeDNA is the only one of the vendors to offer Y DNA testing that includes STR markers and matching between men.

Men who order these tests will be compared for matching on either 37, 111 or 700 STR markers in addition to SNP markers used for haplogroup identification and assignment.

Fathers will certainly match their sons, and paternal line brothers will match each other, but they will also match people more distantly related.

However, if two men are NOT either full or half siblings on the paternal side, they won’t match at 111 markers.

If two men DON’T match, especially at high marker levels, they likely aren’t siblings. The word “likely” is in there because, very occasionally, a large deletion occurs that prevents STR matching, especially at lower levels.

Additionally, men who take the 37 or 111 marker test also receive an estimated haplogroup at a high level for free, without any additional testing.

However, if men take the Big Y-700 test, they not only will (or won’t) match on up to 700 STR markers, they will also receive a VERY refined haplogroup via SNP marker testing that is often even more sensitive in terms of matching than STR markers. Between these two types of markers, Y DNA testing can place men very granularly in relation to other men.

Men can match in two ways on Y DNA, and the results are very enlightening.

If two men match on BOTH their most refined haplogroup (Big Y test) AND STR markers, they could certainly be siblings or father/son. They could also be related on the same line for another reason, such as known or unknown cousins or closer relationships like uncle/nephew. Of course, Y DNA, in addition to autosomal matching, is a powerful combination.

Conversely, if two men don’t have a similar or close haplogroup, they are not a father and son or paternal line siblings.

FamilyTreeDNA offers both inexpensive entry-level testing (37 and 111 markers) and highly refined advanced testing of most of the Y chromosome (Big Y-700), so haplogroup assignments can vary widely based on the test you take. This makes haplogroup matching and interpretation a bit more complex.

For example, haplogroups R-M269 and I-BY14000 are not related in thousands of years. One is haplogroup R, and one is haplogroup I – completely different branches of the Y DNA tree. These two men won’t match on STR markers or their haplogroup.

However, because FamilyTreeDNA provides over 50,000 different haplogroups, or tree branches, for Big Y testers, and they provide VERY granular matching, two father/son or sibling males who have BOTH tested at the Big Y-700 level will have either the exact same haplogroup, or at most, one branch difference on the tree if a mutation occurred between father and son.

If both men have NOT tested at the Big Y-700 level, their haplogroups will be on the same branch. For example, a man who has only taken a 37/111 marker STR test may be estimated at R-M269, which is certainly accurate as far as it goes.

His sibling who has taken a Big Y test will be many branches further downstream on the tree – but on the same large haplogroup R-M269 branch. It’s essential to pay attention to which tests a Y DNA match has taken when analyzing the match.

The beauty of the two kinds of tests is that even if one haplogroup is very general due to no Big Y test, their STR markers should still match. It’s just that sometimes this means that one hand is tied behind your back.

Y DNA matching alone can eliminate the possibility of a direct paternal line connection, but it cannot prove siblingship or paternity alone – not without additional information.

The Advanced Matching tool will provide a list of matches in all categories selected – in this case, both the 111 markers and the Family Finder test. You can see that one of these men is the father of the tester, and one is the full sibling.

You can view haplogroup assignments on the public Y DNA tree, here. I wrote about using the public tree, here.

In addition, recently, FamilyTreeDNA launched the new Y DNA Discover tool, which explains more about haplogroups, including their ages and other fun facts like migration paths along with notable and ancient connections. I wrote about using the Discover tool, here.

Y DNA at 23andMe

Testers receive a base haplogroup with their autosomal test. 23andMe tests a limited number of Y DNA SNP locations, but they don’t test many, and they don’t test STR markers, so there is no Y DNA matching and no refined haplogroups.

You can view the haplogroups of your matches. If your male sibling match does NOT share the same haplogroup, the two men are not paternal line siblings. If two men DO share the same haplogroup, they MIGHT be paternal siblings. They also might not.

Again, autosomal close matching plus haplogroup comparisons include or exclude paternal side siblings for males.

Paternal side siblings at 23andMe share the same haplogroup, but so do many other people. These two men could be siblings. The haplogroups don’t exclude that possibility. If the haplogroups were different, that would exclude being either full or paternal half-siblings.

Men can also compare their mitochondrial DNA to eliminate a maternal relationship.

These men are not full siblings or maternal half-siblings. We know, unquestionably, because their mitochondrial haplogroups don’t match.

23andMe also constructs a genetic tree, but often struggles with close relative placement, especially when half-relationships are involved. I do not recommend relying on the genetic tree in this circumstance.

Mitochondrial DNA

Mitochondrial DNA is passed from mothers to all of their children, but only females pass it on. If two people, males or females, don’t match on their mitochondrial DNA test, with a couple of possible exceptions, they are NOT full siblings, and they are NOT maternal half-siblings.

Mitochondrial DNA at 23andMe

23andMe provides limited, base mitochondrial haplogroups, but no matching. If two people don’t have the same haplogroup at 23andMe, they aren’t full or maternal siblings, as illustrated above.

Mitochondrial DNA at FamilyTreeDNA

FamilyTreeDNA provides both mitochondrial matching AND a much more refined haplogroup. The full sequence test (mtFull), the only version sold today, is essential for reliable comparisons.

Full siblings or maternal half-siblings will always share the same haplogroup, regardless of their sex.

Generally, a full sibling or maternal half-sibling match will match exactly at the full mitochondrial sequence (FMS) level with a genetic distance of zero, meaning fully matching and no mismatching mutations.

There are rare instances where maternal siblings or even mothers and children do not match exactly, meaning they have a genetic distance of greater than 0, because of a mutation called a heteroplasmy.

I wrote about heteroplasmies, here.

Like Y DNA, mitochondrial DNA cannot identify a sibling or parental relationship without additional evidence, but it can exclude one, and it can also provide much-needed evidence in conjunction with autosomal matching. The great news is that unlike Y DNA, everyone has mitochondrial DNA and it comes directly from their mother.

Once again, FamilyTreeDNA’s Advanced Matching tool provides a list of people who match you on both your mitochondrial DNA test and the Family Finder autosomal test, including transfers/uploads, and provides a relationship.

You can see that our tester matches both a full sibling and their mother. Of course, a parent/child match could mean that our tester is a female and one of her children, of either sex, has tested.

Below is an example of a parent-child match that has experienced a heteroplasmy.

Based on the comparison of both the mitochondrial DNA test, plus the autosomal Family Finder test, you can verify that this is a close family relationship.

You can also eliminate potential relationships based on the mitochondrial DNA inheritance path. The mitochondrial DNA of full siblings and maternal half-siblings will always match at the full sequence and haplogroup level, and paternal half-siblings will never match. If paternal half-siblings do match, it’s happenstance or because of a different reason.

Sibling Summary and Checklist

I’ve created a quick reference checklist for you to use when attempting to determine whether or not a match is a sibling, and, if so, whether they are half or full siblings. Of course, these tools are in addition to the DNAPainter Shared cM Tool and GEDmatch’s Relationship Predictor Calculator.

FamilyTreeDNA Ancestry 23andMe MyHeritage GEDmatch
Matching Yes Yes Yes Yes Yes
Shared Matches Yes – In Common With Yes – Shared Matches Yes – Relatives in Common Yes – Review DNA Match Yes – People who match both or 1 of 2 kits
Relationship Between Shared Matches No No No Yes, under shared match No
Matches Match Each Other* Yes, Matrix No Yes, under “View DNA details,” then, “compare with more relatives” Partly, through triangulation Yes, can match any kits
Full Siblings Yes Sibling, implies full Yes Brother, Sister, means full No
Half Siblings Sibling, Uncle/Aunt-Niece/Nephew, Grandparent-Grandchild Close Family – 1C Yes Half sibling, aunt/uncle-niece-nephew No
Fully Identical Regions (FIR) No No Yes No Yes
Half Identical Regions (HIR) No No Yes No Yes
X matching Yes No Yes No Yes
Unusual Reporting or Anomalies No No, Timber is not used on close relationships X match added into total, FIR added twice No Matching amount can vary from vendors
Y DNA Yes, STRs, refined haplogroups, matching No High-level haplogroup only, no matching No No, only if tester enters haplogroup manually
Mitochondrial DNA Yes, full sequence, matching, refined haplogroup No High-level haplogroup only, no matching No No, only if tester enters haplogroup manually
Combined Tools (Autosomal, X, Y, mtDNA) Yes No No No No

*Autoclusters through Genetic Affairs show cluster relationships of matches to the tester and to each other, but not all matches are included, including close matches. While this is a great tool, it’s not relevant for determining close and sibling relationships. See the article, AutoClustering by Genetic Affairs, here.

Additional Resources

Some of you may be wondering how endogamy affects sibling numbers.

Endogamy makes almost everything a little more complex. I wrote about endogamy and various ways to determine if you have an endogamous heritage, here.

Please note that half-siblings with high cM matches also fall into the range of full siblings (1613-3488), with or without endogamy. This may be, but is not always, especially pronounced in endogamous groups.

As another resource, I wrote an earlier article, Full or Half Siblings, here, that includes some different examples.

Strategy

You have a lot of quills in your quiver now, and I wish you the best if you’re trying to unravel a siblingship mystery.

You may not know who your biological family is, or maybe your sibling doesn’t know who their family is, but perhaps your close relatives know who their family is and can help. Remember, the situation that has revealed itself may be a shock to everyone involved.

Above all, be kind and take things slow. If your unexpected sibling match becomes frightened or overwhelmed, they may simply check out and either delete their DNA results altogether or block you. They may have that reaction before you have a chance to do anything.

Because of that possibility, I recommend performing your analysis quickly, along with taking relevant screenshots before reaching out so you will at least have that much information to work with, just in case things go belly up.

When you’re ready to make contact, I suggest beginning by sending a friendly, short, message saying that you’ve noticed that you have a close match (don’t say sibling) and asking what they know about their family genealogy – maybe ask who their grandparents are or if they have family living in the area where you live. I recommend including a little bit of information about yourself, such as where you were born and are from.

I also refrain from using the word adoption (or similar) in the beginning or giving too much detailed information, because it sometimes frightens people, especially if they know or discover that there’s a painful or embarrassing family situation.

And, please, never, ever assume the worst of anyone or their motives. They may be sitting at their keyboard with the same shocked look on their face as you – especially if they have, or had, no idea. They may need space and time to reach a place of acceptance. There’s just nothing more emotionally boat-capsizing in your life than discovering intimate and personal details about your parents, one or both, especially if that discovery is disappointing and image-altering.

Or, conversely, your sibling may have been hoping and waiting just for you!

Take a deep breath and let me know how it goes!

Please feel free to share this article with anyone who could benefit.

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2021 Favorite Articles

It’s that time of the year again when we welcome the next year.

2021 was markedly different than anything that came before. (Is that ever an understatement!)

Maybe you had more time for genealogy and spent time researching!

So, what did we read in 2021? Which of my blog articles were the most popular?

In reverse order, beginning with number 10, we have:

This timeless article published in 2015 explains how to calculate the amount of any specific heritage you carry based on your ancestors.

Just something fun that’s like your regular pedigree chart, except color coded locations instead of ancestors. Here’s mine

The Autosegment Triangulation Cluster Tool is a brand new tool introduced in October 2021. Created by Genetic Affairs for GEDmatch, this tool combines autoclusters and triangulation.

Many people don’t realize that we actually don’t inherit exactly 25% of our DNA from each grandparent, nor why.

This enlightening article co-authored with statistician Philip Gammon explains how this works, and why it affects all of your matches.

Who doesn’t love learning about ancient DNA and the messages it conveys. Does your Y or mitochondrial DNA match any of these burials? Take a look. You might be surprised.

How can you tell if you are full or half siblings with another person? You might think this is a really straightforward question with an easy answer, but it isn’t. And trust me, if you EVER find yourself in a position of needing to know, you really need to know urgently.

Using simple match, it’s easy to figure how much of your ancestor’s DNA you “should” have, but that’s now how inheritance actually works. This article explains why and shows different inheritance scenarios.

That 28 day timer has expired, but the article can still be useful in terms of educating yourself. This should also be read in conjunction with Ancestry Retreats, by Judy Russell.

If I had a dollar for every time I’ve heard someone say that their ethnicity percentages were “wrong,” I’d be a rich woman, living in a villa in sun-drenched Tuscany😊

This extremely popular article has either been first or second every year since it was published. Ethnicity is both exciting and perplexing.

As genealogists, the first thing we need to do is to calculate what, according to our genealogy, we would expect those percentages to be. Of course, we also need to factor in the fact that we don’t inherit exactly the same amount of DNA from each grandparent. I explain how I calculated my “expected” percentages of ethnicity based on my known tree. That’s the best place to start.

Please note that I am no longer updating the vendor comparison charts in the article. Some vendors no longer release updates to the entire database at the same time, and some “tweak” results periodically without making an announcement. You’ll need to compare your own results at the different vendors at the same point in time to avoid comparing apples and oranges.

The #1 Article for 2021 is…

  1. Proving Native American Ancestry Using DNA

This article has either been first (7 times) or second (twice) for 9 years running. Now you know why I chose this topic for my new book, DNA for Native American Genealogy.

If you’re searching for your Native American ancestry, I’ve provided step-by-step instructions, both with and without some percentage of Native showing in your autosomal DNA percentages.

Make 2022 a Great Year!

Here’s wishing you the best in 2022. I hope your brick walls cave. What are you doing to help that along? Do you have a strategy in mind?

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Most Popular Articles of 2020

We all know that 2020 was a year like no other, right? So, what were we reading this year as we spent more time at home?

According to my blog stats, these are the ten most popular articles of 2020.

2020 Rank Blog Article Name Publication Date/Comment
1 Concepts – Calculating Ethnicity Percentages Jan 11, 2017
2 Proving Native American Ancestry Using DNA December 18, 2012
3 Ancestry to Remove DNA Matches Soon – Preservation Strategies with Detailed Instructions Now obsolete article – July 16, 2020
4 Ancestral DNA Percentages – How Much of Them is in You? June 27, 2017
5 Full or Half Siblings? April 3, 2019
6 442 Ancient Viking Skeletons Hold DNA Surprises – Does Your Y or Mitochondrial DNA Match? September 18, 2020
7 Migration Pedigree Chart March 25, 2016
8 DNA Inherited from Grandparents and Great-Grandparents January 14, 2020
9 Optimizing Your Tree at Ancestry for More Hints and DNA ThruLines February 22, 2020
10 Phylogenetic Tree of Novel Coronavirus (hCoV-19) Covid-19 March 12, 2020

Half of these articles were published this year, and half are older.

One article is now obsolete. The Ancestry purge has already happened, so there’s nothing to be done now.

Let’s take a look at the rest and what messages might be held in these popular selections.

Ethnicity

I’m not the least bit surprised by ethnicity being the most popular topic, nor that Concepts – Calculating Ethnicity Percentages is the most popular article. Not only is ethnicity a perennially favorite, but all four major vendors introduced something new this year.

By the way, my perennial caveat still applies – ethnicity is only an estimate😊

While Genetic Groups isn’t actually ethnicity, per se, it’s a layer on top of ethnicity that provides you with locations where your ancestors might have been from and migrated to, based on genetic clusters. Clusters are defined by the locations of ancestors of other people within that genetic cluster.

There’s actually good news at 23andMe. Since this article was published in October, 23andMe has indeed updated the V3 and V4 kits with new ethnicity updates. 23andMe had originally stated they weren’t going to do that, clearly in the hope that people would pay to retest by purchasing the V5 Health + Ancestry test. I’m so glad to see their reversal.

Viewing the older V2 kits, the “updated” date at the bottom of their Ancestry Composition page says they were updated on December 9th or 10th, but I don’t see a difference and they don’t have the “updated” icon like the V3 and V4 kits do.

23andMe made another reversal too and also restored the original matches. They had reduced the number of matches to 1500 for non-Health+Ancestry testers who don’t also subscribe. If you wanted between 1500 and 5000 matches, you had to retest and subscribe for $29 per year. (It’s worth noting that I have over 5000 matches at all of the other vendors.)

To date, 23andMe has restored previous matches and also restored some but not all of the search functionality that they had removed.

What isn’t clear is whether 23andMe will continue to add to this number of matches until the tester reaches the earlier limit of 2000, or whether they have simply restored the previous matches, but the match total will not increase unless you have a subscription.

Consumer feedback works – so thanks to everyone who provided feedback to 23andMe.

Native American Ancestry

The article, Proving Native American Ancestry Using DNA, written 8 years ago, only 5 months after launching this blog, has been in the top 10 every year since I’ve been counting.

I created a Native American reference and resource page too, which you can find here.

I’ll also be publishing some new articles after the first of the year which I promise you’ll find VERY INTERESTING. Something to look forward to.

Understanding Autosomal DNA

2020 has seen more people delving into genealogy + DNA testing which means they need to understand both the results and the concepts underlying their results.

Whooohooo – more people in the pool. Jump on in – the water’s fine!

The articles Ancestral DNA Percentages – How Much of Them is in You? and DNA Inherited from Grandparents and Great-Grandparents both explain how DNA is passed from your ancestors to you.

These are great basic articles if you’re looking to help someone new, and so is First Steps When Your DNA Results are Ready – Sticking Your Toe in the Genealogy Water.

I always look forward to the end of January because there will be lots of matches from holiday gifts being posted. Feel free to forward any of these articles to your new matches. It’s always fun helping new people because you just never know when they might be able to help you.

Surprises

With more and more people testing, more and more people are receiving “surprises” in their results. Need to figure out the difference between full and half-siblings? Then Full or Half Siblings? is the article for you.

Trying to discern other relationships? My favorite tool is the Shared cM Project tool at DNAPainter, here.

Vikings

Who doesn’t want to know if they are related to the ancient Vikings??? You can make that discovery in the article, 442 Ancient Viking Skeletons Hold DNA Surprises – Does Your Y or Mitochondrial DNA Match?. Not only is this just plain fun, but I snuck in a little education too.

Of course, you’ll need to have your Y DNA or mitochondrial DNA results, which you can easily order, here. If you’re unsure and would like to read a short article about the different kinds of DNA and how they can help you, 4 Kinds of DNA for Genetic Genealogy is perfect.

Do you think your DNA isn’t Viking because your ancestors aren’t from Scandinavia? Guess again!

Those Vikings didn’t stay home, and they didn’t restrict their escapades to the British Isles either.

This drawing depicts Viking ships besieging Paris in the year 845. Vikings voyaged into Russia and as far as the Mediterranean.

Have a child studying at home? This might be an interesting topic!

Migration Pedigree Chart

Another just plain fun idea is the Migration Pedigree Chart.

I created this migration pedigree chart in a spreadsheet, but you can also create a pedigree chart in genealogy software with whatever “names” you want. This will also help you figure out the estimated percentages of ethnicity you might reasonably expect.

Another idea for helping kids learn at home and they might accidentally learn about figuring percentages in the process.

ThruLines

ThruLines is the Ancestry tool that assists DNA testers with trees connect the dots to common ancestors with their matches. There are ways to optimize your tree to improve your connections, both in terms of accuracy and the number of Thrulines that form.

Optimizing Your Tree at Ancestry for More Hints and DNA ThruLines provides step by step instructions, which reminds me – I need to write a similar article for MyHeritage’s Theories of Family Relativity. I keep meaning to…

Covid

You know, it wouldn’t be 2020 if I didn’t HAVE to mention that word.

I’m glad to know that people were and hopefully still are educating themselves about Covid. Phylogenetic Tree of Novel Coronavirus (hCoV-19) Covid-19 reflected early information about the novel virus and our first efforts to sequence the DNA. Of course, as expected, just like any other organism, mutations have occurred since then.

Goodness knows, we are all tired of Covid and the resulting safety protocols. Keep on keeping on. We need you on the other side.

Stay home, mask up when you must leave, stay away from other people outside your family that you live with, wash your hands, and get vaccinated as soon as you can.

And until we can all see each other in person again, hopefully, sooner than later, keep on doing genealogy.

Locked in the Library

Be careful what you ask for.

Remember that dream where you’re locked in a library? Remember saying you don’t have enough time for genealogy?

Well, now you are and now you do.

The library is your desk with your computer or maybe your laptop on a picnic table in the yard.

DNA results, matches, and research tools are the books and you’re officially locked in for at least a few more weeks. Free articles like these are your guide.

Hmmm, pandemic isolation doesn’t sound so bad now, does it??

We’ll just rename it “genealogy library lock-in.”

Happy New Year!

What can you discover?

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

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Genealogy Research

Books

Top 10 All-Time Favorite DNA Articles

Top 10

I’ve been writing about DNA is every shape and form for approaching 8 years now, offering more than 1200 free (key word seachable) articles.

First, thank you for being loyal subscribers or finding my articles and using them to boost your genealogy research with the power of DNA.

You may not know this, but many of my articles stem from questions that blog readers ask, plus my own genealogical research stumbling-blocks, of course.

DNAeXplain articles have accumulated literally millions and millions of page views, generating more than 38,000 approved comments. Yes, I read and approve (or not) every single comment. No, I do not have “staff” to assist. Staff consists of some very helpful felines who would approve any comment with the word catnip😊

More than twice that number of comments were relegated to spam. That’s exactly why I approve each one personally.

Old Faithful

Looking at your favorites, I’ve discovered that some of these articles have incredible staying power, meaning that people access them again and again. Given their popularity and usefulness, please feel free to share by linking or forwarding to your friends and genealogy groups.

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Your Favorites

You didn’t realize it, but every time you click, you’re voting.

So, which articles are reader favorites? Remember that older articles have had more time to accumulate views.

I’ve noted the all-time ranking along with the 2019 ranking.

Starting with number 10, you chose:

  • Number 10 all-time, did not place in top 10 in 2019: Ethnicity Testing – A Conundrum – Published in 2016 – How ethnicity testing works – and why sometimes it doesn’t work like people expect it will.

Ethnicity results from DNA testing. Fascinating. Intriguing. Frustrating. Exciting. Fun. Challenging. Mysterious. Enlightening. And sometimes wrong. These descriptions all fit. Welcome to your personal conundrum! The riddle of you! If you’d like to understand why your ethnicity results might not have … Continue reading →

  • Number 9 all time and number 4 in 2019: How Much Indian Do I Have in Me? – Published in 2015 – This article explains how to convert that family story into an expected percentage.

I can’t believe how often I receive this question. Here’s today’s version from Patrick. “My mother had 1/8 Indian and my grandmother on my father’s side was 3/4, and my grandfather on my father’s side had 2/3. How much would … Continue reading →

  • Number 8 all-time, did not place in top 10 in 2019: 4 Kinds of DNA for Genetic Genealogy – Published in 2012 – Short, basic and THE article I refer people to most often to understand DNA for genealogy.

Let’s talk about the different “kinds” of DNA and how they can be used for genetic genealogy. It used to be simple. When this “industry” first started, in the year 2000, you could test two kinds of DNA and it was … Continue reading →

Yep, there’s a gene for these traits, and more. The same gene, named EDAR (short for Ectodysplasin receptor EDARV370A), it turns out, also confers more sweat glands and distinctive teeth and is found in the majority of East Asian people. This is one … Continue reading →

  • Number 6 all-time, did not place in top 10 in 2019: What is a Haplogroup? – Published in 2013 – One of the first questions people ask about Y and mitochondrial DNA is about haplogroups.

Sometimes we’ve been doing genetic genealogy for so long we forget what it’s like to be new. I’m reminded, sometimes humorously, by some of the questions I receive. When I do DNA Reports for clients, each person receives a form to … Continue reading

  • Number 5 all-time and number 10 in 2019: X Marks the Spot – Published in 2012 – This article explains how to use the X chromosome for genealogy and its unique inheritance path.

When using autosomal DNA, the X chromosome is a powerful tool with special inheritance properties. Many people think that mitochondrial DNA is the same as the X chromosome. It’s not. Mitochondrial DNA is inherited maternally, only. This means that mothers … Continue reading →

  • Number 4 all-time, did not place in top 10 in 2019: Ethnicity Results – True or Not? – Published in 2013 – Are your ethnicity results accurate? How can you know, and why might your percentages reflect something different than you expect?

I can’t even begin to tell you how many questions I receive that go something like this: “I received my ethnicity results from XYZ. I’m confused. The results don’t seem to align with my research and I don’t know what … Continue reading →

  • Number 3 all-time and number 1 in 2019: Concepts – Calculating Ethnicity Percentages – Published in 2017 – With the huge number of ethnicity testers, it’s no surprise that the most popular article discussed how those percentages are calculated.

There has been a lot of discussion about ethnicity percentages within the genetic genealogy community recently, probably because of the number of people who have recently purchased DNA tests to discover “who they are.” Testers want to know specifically if ethnicity percentages are right … Continue reading →

  • Number 2 all-time, did not place in top 10 in 2019: Which DNA Test is Best? – Published in 2017 – A comprehensive review of the tests and major vendors in the genetic genealogy testing space. The answer is that your testing goals determine which test is best. This article aligns goals with tests.

If you’re reading this article, congratulations. You’re a savvy shopper and you’re doing some research before purchasing a DNA test. You’ve come to the right place. The most common question I receive is asking which test is best to purchase. There is … Continue reading →

Every day, I receive e-mails very similar to this one. “My family has always said that we were part Native American.  I want to prove this so that I can receive help with money for college.” The reasons vary, and … Continue reading →

2019 Only

Five articles ranked in the top 10 in 2019 that aren’t in the top all-time 10 articles. Two were just published in 2019.

  • Number 8 for 2019: Migration Pedigree Chart – Published in 2016 – This fun article illustrates how to create a pedigree charting focused on the locations of your ancestors.

Paul Hawthorne started a bit of a phenomenon, whether he meant to or not, earlier this week on Facebook, when he created a migration map of his own ancestors using Excel to reflect his pedigree chart. You can view … Continue reading →

Just as they promised, and right on schedule, Family Tree DNA today announced X chromosome matching. They have fully integrated X matching into their autosomal Family Finder product matching. This will be rolling live today. Happy New Year from Family … Continue reading →

  • Number 6 for 2019: Full or Half Siblings – Published in April 2019 – Want to know how to determine the difference between full and half siblings? This is it.

Many people are receiving unexpected sibling matches. Every day on social media, “surprises” are being reported so often that they are no longer surprising – unless of course you’re the people directly involved and then it’s very personal, life-altering and you’re … Continue reading →

Ancestry’s new tool, ThruLines has some good features and a lot of potential, but right now, there are a crop of ‘gators in the swimmin’ hole – just waiting for the unwary. Here’s help to safely navigate the waters and … Continue reading →

One of the most common questions I receive, especially in light of the interest in ethnicity testing, is how much of an ancestor’s DNA someone “should” share. The chart above shows how much of a particular generation of ancestors’ DNA … Continue reading →

In Summary

Taking a look at a summary chart is interesting. From my perspective, I never expected the “Thick Hair, Small Boobs” article to be so popular.

“Which DNA Test is Best?” ranked #2 all time, but not in the 2019 top 10. I wonder if that is a function of the market softening a bit, or of fewer people researching before purchasing.

I was surprised that 5 of the top 10 all-time were not in the top 10 of 2019.

Conversely, I’m equally as surprised that 3 of the older 2019 articles not in the all-time top 10.

I’m very glad these older articles continue to be useful, and I do update them periodically, especially if I notice they are accessed often.

Article All-time Top 10 2019 Top 10
Ethnicity Testing – A Conundrum 10 0
How Much Indian Do I Have in Me? 9 4
4 Kinds of DNA for Genetic Genealogy 8 0
Thick Hair, Small Boobs, Shovel Shaped Teeth, and More 7 9
What is a Haplogroup? 6 0
X Marks the Spot 5 10
Ethnicity Results – True or Not? 4 0
Concepts – Calculating Ethnicity Percentages 3 1
Which DNA Test is Best? 2 0
Proving Native American Ancestry Using DNA 1 2
Migration Pedigree Chart 0 8
X Chromosome Matching at Family Tree DNA 0 7
Full or Half Siblings Published in 2019 6
Ancestry’s ThruLines Dissected: How to Use and Not get Bit by the ‘Gators Published in 2019 5
Ancestral DNA Percentages – How Much of Them is in You? 0 3

What Would You Like to See in 2020?

Given that your questions are often my inspiration, what articles would you like to see in 2020?

Are there topics you’d like to see covered? (Sorry, I don’t know the name of your great-great-grandfather’s goat.)

Burning questions you’d like to have answered? (No, I don’t know why there is air.)

Something you’ve been wishing for? (Except maybe for the 1890 census.)

Leave a comment and let me know. (Seriously😊)

I’m looking forward to a wonderful 2020 and hope you’ll come along!

_____________________________________________________________

Disclosure

I receive a small contribution when you click on some (but not all) of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Services

Genealogy Research

2019: The Year and Decade of Change

2019 ends both a year and a decade. In the genealogy and genetic genealogy world, the overwhelmingly appropriate word to define both is “change.”

Everything has changed.

Millions more records are online now than ever before, both through the Big 3, being FamilySearch, MyHeritage and Ancestry, but also through multitudes of other sites preserving our history. Everyplace from National Archives to individual blogs celebrating history and ancestors.

All you need to do is google to find more than ever before.

I don’t know about you, but I’ve made more progress in the past decade that in all of the previous ones combined.

Just Beginning?

If you’re just beginning with genetic genealogy, welcome! I wrote this article just for you to see what to expect when your DNA results are returned.

If you’ve been working with genetic genealogy results for some time, or would like a great review of the landscape, let’s take this opportunity to take a look at how far we’ve come in the past year and decade.

It’s been quite a ride!

What Has Changed?

EVERYTHING

Literally.

A decade ago, we had Y and mitochondrial DNA, but just the beginning of the autosomal revolution in the genetic genealogy space.

In 2010, Family Tree DNA had been in business for a decade and offered both Y and mitochondrial DNA testing.

Ancestry offered a similar Y and mtDNA product, but not entirely the same markers, nor full sequence mitochondrial. Ancestry subsequently discontinued that testing and destroyed the matching database. Ancestry bought the Sorenson database that included Y, mitochondrial and autosomal, then destroyed that data base too.

23andMe was founded in 2006 and began autosomal testing in 2007 for health and genealogy. Genealogists piled on that bandwagon.

Family Tree DNA added autosomal to their menu in 2010, but Ancestry didn’t offer an autosomal product until 2012 and MyHeritage not until 2016. Both Ancestry and MyHeritage have launched massive marketing and ad campaigns to help people figure out “who they are,” and who their ancestors were too.

Family Tree DNA

2019 FTDNA

Family Tree DNA had a banner year with the Big Y-700 product, adding over 211,000 Y DNA SNPs in 2019 alone to total more than 438,000 by year end, many of which became newly defined haplogroups. You can read more here. Additionally, Family Tree DNA introduced the Block Tree and public Y and public mitochondrial DNA trees.

Anyone who ignores Y DNA testing does so at their own peril. Information produced by Y DNA testing (and for that matter, mitochondrial too) cannot be obtained any other way. I wrote about utilizing mitochondrial DNA here and a series about how to utilize Y DNA begins in a few days.

Family Tree DNA remains the premier commercial testing company to offer high resolution and full sequence testing and matching, which of course is the key to finding genealogy solutions.

In the autosomal space, Family Tree DNA is the only testing company to provide Phased Family Matching which uses your matches on both sides of your tree, assuming you link 3rd cousins or closer, to assign other testers to specific parental sides of your tree.

Family Tree DNA accepts free uploads from other testing companies with the unlock for advanced features only $19. You can read about that here and here.

MyHeritage

MyHeritage, the DNA testing dark horse, has come from behind from their late entry into the field in 2016 with focused Europeans ads and the purchase of Promethease in 2019. Their database stands at 3.7 million, not as many as either Ancestry or 23andMe, but for many people, including me – MyHeritage is much more useful, especially for my European lines. Not only is MyHeritage a genealogy company, piloted by Gilad Japhet, a passionate genealogist, but they have introduced easy-to-use advanced tools for consumers during 2019 to take the functionality lead in autosomal DNA.

2019 MyHeritage.png

You can read more about MyHeritage and their 2019 accomplishments, here.

As far as I’m concerned, the MyHeritage bases-loaded 4-product “Home Run” makes MyHeritage the best solution for genetic genealogy via either testing or transfer:

  • Triangulation – shows testers where 3 or more people match each other. You can read more, here.
  • Tree Matching – SmartMatching for both DNA testers and those who have not DNA tested
  • Theories of Family Relativity – a wonderful new tool introduced in February. You can read more here.
  • AutoClusters – Integrated cluster technology helps you to visualize which groups of people match each other.

One of their best features, Theories of Family Relativity connects the dots between people you DNA match with disparate trees and other documents, such as census. This helps you and others break down long-standing brick walls. You can read more, here.

MyHeritage encourages uploads from other testing companies with basic functions such as matching for free. Advanced features cost either a one-time unlock fee of $29 or are included with a full subscription which you can try for free, here. You can read about what is free and what isn’t, here.

You can develop a testing and upload strategy along with finding instructions for how to upload here and here.

23andMe

Today, 23andMe is best known for health, having recovered after having had their wings clipped a few years back by the FDA. They were the first to offer Health results, leveraging the genealogy marketspace to attract testers, but have recently been eclipsed by both Family Tree DNA with their high end full Exome Tovana test and MyHeritage with their Health upgrade which provides more information than 23andMe along with free genetic counseling if appropriate. Both the Family Tree DNA and MyHeritage tests are medically supervised, so can deliver more results.

23andMe has never fully embraced genetic genealogy by adding the ability to upload and compare trees. In 2019, they introduced a beta function to attempt to create a genetic tree on your behalf based on how your matches match you and each other.

2019 23andMe.png

These trees aren’t accurate today, nor are they deep, but they are a beginning – especially considering that they are not based on existing trees. You can read more here.

The best 23andMe feature for genealogy, as far as I’m concerned, is their ethnicity along with the fact that they actually provide testers with the locations of their ethnicity segments which can help testers immensely, especially with minority ancestry matching. You can read about how to do this for yourself, here.

23andMe generally does not allow uploads, probably because they need people to test on their custom-designed medical chip. Very rarely, once that I know of in 2018, they do allow uploads – but in the past, uploaders do not receive all of the genealogy features and benefits of testing.

You can however, download your DNA file from 23andMe and upload elsewhere, with instructions here.

Ancestry

Ancestry is widely known for their ethnicity ads which are extremely effective in recruiting new testers. That’s the great news. The results are frustrating to seasoned genealogists who get to deal with the fallout of confused people trying to figure out why their results don’t match their expectations and family stories. That’s the not-so-great news.

However, with more than 15 million testers, many of whom DO have genealogy trees, a serious genealogist can’t *NOT* test at Ancestry. Testers do need to be aware that not all features are available to DNA testers who don’t also subscribe to Ancestry’s genealogy subscriptions. For example, you can’t see your matches’ trees beyond a 5 generation preview without a subscription. You can read more about what you do and don’t receive, here.

Ancestry is the only one of the major companies that doesn’t provide a chromosome browser, despite pleas for years to do so, but they do provide ThruLines that show you other testers who match your DNA and show a common ancestor with you in their trees.

2019 Ancestry.png

ThruLines will also link partial trees – showing you ancestral descendants from the perspective of the ancestor in question, shown above. You can read about ThruLines, here.

Of course, without a chromosome browser, this match is only as good as the associated trees, and there is no way to prove the genealogical connection. It’s possible to all be wrong together, or to be related to some people through a completely different ancestor. Third party tools like Genetic Affairs and cluster technology help resolve these types of issues. You can read more, here.

You can’t upload DNA files from other testing companies to Ancestry, probably due to their custom medical chip. You can download your file from Ancestry and upload to other locations, with instructions here.

Selling Customers’ DNA

Neither Family Tree DNA, MyHeritage nor Gedmatch sell, lease or otherwise share their customers’ DNA, and all three state (minimally) they will not in the future without prior authorization.

All companies utilize their customers’ DNA internally to enhance and improve their products. That’s perfectly normal.

Both Ancestry and 23andMe sell consumers DNA to both known and unknown partners if customers opt-in to additional research. That’s the purpose of all those questions.

If you do agree or opt-in, and for those who tested prior to when the opt-in began, consumers don’t know who their DNA has been sold to, where it is or for what purposes it’s being utilized. Although anonymized (pseudonymized) before sale, autosomal results can easily be identified to the originating tester (if someone were inclined to do so) as demonstrated by adoptees identifying parents and law enforcement identifying both long deceased remains and criminal perpetrators of violent crimes. You can read more about re-identification here, although keep in mind that the re-identification frequency (%) would be much higher now than it was in 2018.

People are widely split on this issue. Whatever you decide, to opt-in or not, just be sure to do your homework first.

Always read the terms and conditions fully and carefully of anything having to do with genetics.

Genealogy

The bottom line to genetic genealogy is the genealogy aspect. Genealogists want to confirm ancestors and discover more about those ancestors. Some information can only be discovered via DNA testing today, distant Native heritage, for example, breaking through brick walls.

This technology, as it has advanced and more people have tested, has been a godsend for genealogists. The same techniques have allowed other people to locate unknown parents, grandparents and close relatives.

Adoptees

Not only are genealogists identifying people long in the past that are their ancestors, but adoptees and those seeking unknown parents are making discoveries much closer to home. MyHeritage has twice provided thousands of free DNA tests via their DNAQuest program to adoptees seeking their biological family with some amazing results.

The difference between genealogy, which looks back in time several generations, and parent or grand-parent searches is that unknown-parent searches use matches to come forward in time to identify parents, not backwards in time to identify distant ancestors in common.

Adoptee matching is about identifying descendants in common. According to Erlich et al in an October 2018 paper, here, about 60% of people with European ancestry could be identified. With the database growth since that time, that percentage has risen, I’m sure.

You can read more about the adoption search technique and how it is used, here.

Adoptee searches have spawned their own subculture of sorts, with researchers and search angels that specialize in making these connections. Do be aware that while many reunions are joyful, not all discoveries are positively received and the revelations can be traumatic for all parties involved.

There’s ying and yang involved, of course, and the exact same techniques used for identifying biological parents are also used to identify cold-case deceased victims of crime as well as violent criminals, meaning rapists and murderers.

Crimes Solved

The use of genetic genealogy and adoptee search techniques for identifying skeletal remains of crime victims, as well as identifying criminals in order that they can be arrested and removed from the population has resulted in a huge chasm and division in the genetic genealogy community.

These same issues have become popular topics in the press, often authored by people who have no experience in this field, don’t understand how these techniques are applied or function and/or are more interested in a sensational story than in the truth. The word click-bait springs to mind although certainly doesn’t apply equally to all.

Some testers are adamantly pro-usage of their DNA in order to identify victims and apprehend violent criminals. Other testers, not so much and some, on the other end of the spectrum are vehemently opposed. This is a highly personal topic with extremely strong emotions on both sides.

The first such case was the Golden State Killer, which has been followed in the past 18 months or so by another 100+ solved cases.

Regardless of whether or not people want their own DNA to be utilized to identify these criminals and victims, providing closure for families, I suspect the one thing we can all agree on is that we are grateful that these violent criminals no longer live among us and are no longer preying on innocent victims.

I wrote about the Golden State Killer, here, as well as other articles here, here, here and here.

In the genealogy community, various vendors have adopted quite different strategies relating to these kinds of searches, as follows:

  • Ancestry, 23andMe and MyHeritage – have committed to fight all access attempts by law enforcement, including court ordered subpoenas.
  • MyHeritage, Family Tree DNA and GedMatch allow uploads, so forensic kits, meaning kits from deceased remains or rape kits could be uploaded to search for matches, the same as any other kit. Law Enforcement uploads violate the MyHeritage terms of service. Both Family Tree DNA and GEDmatch have special law enforcement procedures in place. All three companies have measures in place to attempt to detect unauthorized forensic uploads.
  • Family Tree DNA has provided a specific Law Enforcement protocol and guidelines for forensic uploads, here. All EU customers were opted out earlier in 2019, but all new or existing non-EU customers need to opt out if they do not want their DNA results available for matching to law enforcement kits.
  • GEDmatch was recently sold to Verogen, a DNA forensics company, with information, here. Currently GEDMatch customers are opted-out of matching for law enforcement kits, but can opt-in. Verogen, upon purchase of GEDmatch, required all users to read the terms and conditions and either accept the terms or delete their kits. Users can also delete their kits or turn off/on law enforcement matching at any time.

New Concerns

Concerns in late 2019 have focused on the potential misuse of genetic matching to potentially target subsets of individuals by despotic regimes such as has been done by China to the Uighurs.

You can read about potential risks here, here and here, along with a recent DoD memo here.

Some issues spelled out in the papers can be resolved by vendors agreeing to cryptographically sign their files when customers download. Of course, this would require that everyone, meaning all vendors, play nice in the sandbox. So far, that hasn’t happened although I would expect that the vendors accepting uploads would welcome cryptographic signatures. That pretty much leaves Ancestry and 23andMe. I hope they will step up to the plate for the good of the industry as a whole.

Relative to the concerns voiced in the papers and by the DoD, I do not wish to understate any risks. There ARE certainly risks of family members being identified via DNA testing, which is, after all, the initial purpose even though the current (and future) uses were not foreseen initially.

In most cases, the cow has already left that barn. Even if someone new chooses not to test, the critical threshold is now past to prevent identification of individuals, at least within the US and/or European diaspora communities.

I do have concerns:

  • Websites where the owners are not known in the genealogical community could be collecting uploads for clandestine purposes. “Free” sites are extremely attractive to novices who tend to forget that if you’re not paying for the product, you ARE the product. Please be very cognizant and leery. Actually, just say no unless you’re positive.
  • Fearmongering and click-bait articles in general will prevent and are already causing knee-jerk reactions, causing potential testers to reject DNA testing outright, without doing any research or reading terms and conditions.
  • That Ancestry and 23andMe, the two major vendors who don’t accept uploads will refuse to add crypto-signatures to protect their customers who download files.

Every person needs to carefully make their own decisions about DNA testing and participating in sharing through third party sites.

Health

Not surprisingly, the DNA testing market space has cooled a bit this past year. This slowdown is likely due to a number of factors such as negative press and the fact that perhaps the genealogical market is becoming somewhat saturated. Although, I suspect that when vendors announce major new tools, their DNA kit sales spike accordingly.

Look at it this way, do you know any serious genealogists who haven’t DNA tested? Most are in all of the major databases, meaning Ancestry, 23andMe, FamilyTreeDNA, MyHeritage and GedMatch.

All of the testing companies mentioned above (except GEDmatch who is not a testing company) now have a Health offering, designed to offer existing and new customers additional value for their DNA testing dollar.

23andMe separated their genealogy and health offering years ago. Ancestry and MyHeritage now offer a Health upgrade. For existing customers, FamilyTreeDNA offers the Cadillac of health tests through Tovana.

I would guess it goes without saying here that if you really don’t want to know about potential health issues, don’t purchase these tests. The flip side is, of course, that most of the time, a genetic predisposition is nothing more and not a death sentence.

From my own perspective, I found the health tests to be informative, actionable and in some cases, they have been lifesaving for friends.

Whoever knew genealogy might save your life.

Innovative Third-Party Tools

Tools, and fads, come and go.

In the genetic genealogy space, over the years, tools have burst on the scene to disappear a few months later. However, the last few years have been won by third party tools developed by well-known and respected community members who have created tools to assist other genealogists.

As we close this decade, these are my picks of the tools that I use almost daily, have proven to be the most useful genealogically and that I feel I just “couldn’t live without.”

And yes, before you ask, some of these have a bit of a learning curve, but if you are serious about genealogy, these are all well worthwhile:

  • GedMatch – offers a wife variety of tools including triangulation, half versus fully identical segments and the ability to see who your matches also match. One of the tools I utilize regularly is segment search to see who else matches me on a specific segment, attached to an ancestor I’m researching. GedMatch, started by genealogists, has lasted more than a decade prior to the sale in December 2019.
  • Genetic Affairs – a barn-burning newcomer developed by Evert-Jan Blom in 2018 wins this years’ “Best” award from me, titled appropriately, the “SNiPPY.”.

Genetic Affairs 2019 SNiPPY Award.png

Genetic Affairs offers clustering, tree building between your matches even when YOU don’t have a tree. You can read more here.

2019 genetic affairs.png

Just today, Genetic Affairs released a new cluster interface with DNAPainter, example shown above.

  • DNAPainter – THE chromosome painter created by Jonny Perl just gets better and better, having added pedigree tree construction this year and other abilities. I wrote a composite instructional article, here.
  • DNAGedcom.com and Genetic.Families, affiliated with DNAAdoption.org – Rob Warthen in collaboration with others provides tools like clustering combined with triangulation. My favorite feature is the gathering of all direct ancestors of my matches’ trees at the various vendors where I’ve DNA tested which allows me to search for common surnames and locations, providing invaluable hints not otherwise available.

Promising Newcomer

  • MitoYDNA – a non-profit newcomer by folks affiliated with DNAAdoption and DNAGedcom is designed to replace YSearch and MitoSearch, both felled by the GDPR ax in 2018. This website allows people to upload their Y and mitochondrial DNA results and compare the values to each other, not just for matching, which you can do at Family Tree DNA, but also to see the values that do and don’t match and how they differ. I’ll be taking MitoYDNA for a test drive after the first of the year and will share the results with you.

The Future

What does the future hold? I almost hesitate to guess.

  • Artificial Intelligence Pedigree Chart – I think that in the not-too-distant future we’ll see the ability to provide testers with a “one and done” pedigree chart. In other words, you will test and receive at least some portion of your genealogy all tidily presented, red ribbon untied and scroll rolled out in front of you like you’re the guest on one of those genealogy TV shows.

Except it’s not a show and is a result of DNA testing, segment triangulation, trees and other tools which narrow your ancestors to only a few select possibilities.

Notice I said, “the ability to.” Just because we have the ability doesn’t mean a vendor will implement this functionality. In fact, just think about the massive businesses built upon the fact that we, as genealogists, have to SEARCH incessantly for these elusive answers. Would it be in the best interest of these companies to just GIVE you those answers when you test?

If not, then these types of answers will rest with third parties. However, there’s a hitch. Vendors generally don’t welcome third parties offering advanced tools and therefore block those tools, even though they are being used BY the customer or with their explicit authorization to massage their own data.

On the other hand, as a genealogist, I would welcome this feature with open arms – because as far as I’m concerned, the identification of that ancestor is just the first step. I get to know them by fleshing out their bones by utilizing those research records.

In fact, I’m willing to pony up to the table and I promise, oh-so-faithfully, to maintain my subscription lifelong if one of those vendors will just test me. Please, please, oh pretty-please put me to the test!

I guess you know what my New Year’s Wish is for this and upcoming years now too😊

What About You?

What do you think the high points of 2019 have been?

How about the decade?

What do you think the future holds?

Do you care to make any predictions?

Are you planning to focus on any particular goal or genealogy problem in 2020?

______________________________________________________________

Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

Genealogy Products and Services

Genealogy Research

Fun DNA Stuff

  • Celebrate DNA – customized DNA themed t-shirts, bags and other items

First Steps When Your DNA Results are Ready – Sticking Your Toe in the Genealogy Water

First steps helix

Recently someone asked me what the first steps would be for a person who wasn’t terribly familiar with genealogy and had just received their DNA test results.

I wrote an article called DNA Results – First Glances at Ethnicity and Matching which was meant to show new folks what the various vendor interfaces look like. I was hoping this might whet their appetites for more, meaning that the tester might, just might, stick their toe into the genealogy waters😊

I’m hoping this article will help them get hooked! Maybe that’s you!

A Guide

This article can be read in one of two ways – as an overview, or, if you click the links, as a pretty thorough lesson. If you’re new, I strongly suggest reading it as an overview first, then a second time as a deeper dive. Use it as a guide to navigate your results as you get your feet wet.

I’ll be hotlinking to various articles I’ve written on lots of topics, so please take a look at details (eventually) by clicking on those links!

This article is meant as a guideline for what to do, and how to get started with your DNA matching results!

If you’re looking for ethnicity information, check out the First Glances article, plus here and here and here.

Concepts – Calculating Ethnicity Percentages provides you with guidelines for how to estimate your own ethnicity percentages based on your known genealogy and Ethnicity Testing – A Conundrum explains how ethnicity testing is done.

OK, let’s get started. Fun awaits!

The Goal

The goal for using DNA matching in genealogy depends on your interests.

  1. To discover cousins and family members that you don’t know. Some people are interested in finding and meeting relatives who might have known their grandparents or great-grandparents in the hope of discovering new family information or photos they didn’t know existed previously. I’ve been gifted with my great-grandparent’s pictures, so this strategy definitely works!
  2. To confirm ancestors. This approach presumes that you’ve done at least a little genealogy, enough to construct at least a rudimentary tree. Ancestors are “confirmed” when you DNA match multiple other people who descend from the same ancestor through multiple children. I wrote an article, Ancestors: What Constitutes Proof?, discussing how much evidence is enough to actually confirm an ancestor. Confirmation is based on a combination of both genealogical records and DNA matching and it varies depending on the circumstances.
  3. Adoptees and people with unknown parents seeking to discover the identities of those people aren’t initially looking at their own family tree – because they don’t have one yet. The genealogy of others can help them figure out the identity of those mystery people. I wrote about that technique in the article, Identifying Unknown Parents and Individuals Using DNA Matching.

DNAAdoption for Everyone

Educational resources for adoptees and non-adoptees alike can be found at www.dnaadoption.org. DNAAdoption is not just for adoptees and provides first rate education for everyone. They also provide trained and mentored search angels for adoptees who understand the search process along with the intricacies of navigating the emotional minefield of adoption and unknown parent searches.

First Look” classes for each vendor are free for everyone at DNAAdoption and are self-paced, downloadable onto your computer as a pdf file. Intro to DNA, Applied Autosomal DNA and Y DNA Basics classes are nominally priced at between $29 and $49 and I strongly recommend these. DNAAdoption is entirely non-profit, so your class fee or contribution supports their work. Additional resources can be found here and their 12 adoptee search steps here.

Ok, now let’s look at your results.

Matches are the Key

Regardless of your goal, your DNA matches are the key to finding answers, whether you want to make contact with close relatives, prove your more distant ancestors or you’re involved in an adoptee or unknown parent search.

Your DNA matches that of other people because each of you inherited a piece of DNA, called a segment, where many locations are identical. The length of that DNA segment is measured in centiMorgans and those locations are called SNPs, or single nucleotide polymorphisms. You can read about the definition of a centimorgan and how they are used in the article Concepts – CentiMorgans, SNPs and Pickin’Crab.

While the scientific details are great, they aren’t important initially. What is important is to understand that the more closely you match someone, the more closely you are related to them. You share more DNA with close relatives than more distant relatives.

For example, I share exactly half of my mother’s DNA, but only about 25% of each of my grandparents’ DNA. As the relationships move further back in time, I share less and less DNA with other people who descend from those same ancestors.

Informational Tools

Every vendor’s match page looks different, as was illustrated in the First Glances article, but regardless, you are looking for four basic pieces of information:

  • Who you match
  • How much DNA you share with your match
  • Who else you and your match share that DNA with, which suggests that you all share a common ancestor
  • Family trees to reveal the common ancestor between people who match each other

Every vendor has different ways of displaying this information, and not all vendors provide everything. For example, 23andMe does not support trees, although they allow you to link to one elsewhere. Ancestry does not provide a tool called a chromosome browser which allows you to see if you and others match on the same segment of DNA. Ancestry only tells you THAT you match, not HOW you match.

Each vendor has their strengths and shortcomings. As genealogists, we simply need to understand how to utilize the information available.

I’ll be using examples from all 4 major vendors:

Your matches are the most important information and everything else is based on those matches.

Family Tree DNA

I have tested many family members from both sides of my family at Family Tree DNA using the Family Finder autosomal test which makes my matches there incredibly useful because I can see which family members, in addition to me, my matches match.

Family Tree DNA assigns matches to maternal and paternal sides in a unique way, even if your parents haven’t tested, so long as some close relatives have tested. Let’s take a look.

First Steps Family Tree DNA matches.png

Sign on to your account and click to see your matches.

At the top of your Family Finder matches page, you’ll see three groups of things, shown below.

First Steps Family Tree DNA bucketing

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A row of tools at the top titled Chromosome Browser, In Common With and Not in Common With.

A second row of tabs that include All, Paternal, Maternal and Both. These are the maternal and paternal tabs I mentioned, meaning that I have a total of 4645 matches, 988 of which are from my paternal side and 847 of which are from my maternal side.

Family Tree DNA assigns people to these “buckets” based on matches with third cousins or closer if you have them attached in your tree. This is why it’s critical to have a tree and test close relatives, especially people from earlier generations like aunts, uncles, great-aunts/uncles and their children if they are no longer living.

If you have one or both parents that can test, that’s a wonderful boon because anyone who matches you and one of your parents is automatically bucketed, or phased (scientific term) to that parent’s side of the tree. However, at Family Tree DNA, it’s not required to have a parent test to have some matches assigned to maternal or paternal sides. You just need to test third cousins or closer and attach them to the proper place in your tree.

How does bucketing work?

Maternal or Paternal “Side” Assignment, aka Bucketing

If I match a maternal first cousin, Cheryl, for example, and we both match John Doe on the same segment, John Doe is automatically assigned to my maternal bucket with a little maternal icon placed beside the match.

First Steps Family Tree DNA match info

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Every vendor provides an estimated or predicted relationship based on a combination of total centiMorgans and the longest contiguous matching segment. The actual “linked relationship” is calculated based on where this person resides in your tree.

The common surnames at far right are a very nice features, but not every tester provides that information. When the testers do include surnames at Family Tree DNA, common surnames are bolded. Other vendors have similar features.

People with trees are shown near their profile picture with a blue pedigree icon. Clicking on the pedigree icon will show you their ancestors. Your matches estimated relationship to you indicates how far back you should expect to share an ancestor.

For example, first cousins share grandparents. Second cousins share great-grandparents. In general, the further back in time your common ancestor, the less DNA you can be expected to share.

You can view relationship information in chart form in my article here or utilize DNAPainter tools, here, to see the various possibilities for the different match levels.

Clicking on the pedigree chart of your match will show you their tree. In my tree, I’ve connected my parents in their proper places, along with Cheryl and Don, mother’s first cousins. (Yes, they’ve given permission for me to utilize their results, so they aren’t always blurred in images.)

Cheryl and Don are my first cousins once removed, meaning my mother is their first cousin and I’m one generation further down the tree. I’m showing the amount of DNA that I share with each of them in red in the format of total DNA shared and longest unbroken segment, taken from the match list. So 382-53 means I share a total of 382 cM and 53 cM is the longest matching block.

First Steps Family Tree DNA tree.png

The Chromosome Browser

Utilizing the chromosome browser, I can see exactly where I match both Don and Cheryl. It’s obvious that I match them on at least some different pieces of my DNA, because the total and longest segment amounts are different.

The reason it’s important to test lots of close relatives is because even siblings inherit different pieces of DNA from their parents, and they don’t pass the same DNA to their offspring either – so in each generation the amount of shared DNA is probably reduced. I say probably because sometimes segments are passed entirely and sometimes not at all, which is how we “lose” our ancestors’ DNA over the generations.

Here’s a matching example utilizing a chromosome browser.

First Steps Family Tree DNA chromosome browser.png

I clicked the checkboxes to the left of both Cheryl and Don on the match page, then the Chromosome Browser button, and now you can see, above, on chromosomes 1-16 where I match Cheryl (blue) and Don (red.)

In this view, both Don and Cheryl are being compared to me, since I’m the one signed in to my account and viewing my DNA matches. Therefore, one of the bars at each chromosome represents Don’s DNA match to me and one represents Cheryl’s. Cheryl is the first person and Don is the second. Person match colors (red and blue) are assigned arbitrarily by the system.

My grandfather and Cheryl/Don’s father, Roscoe, were siblings.

You can see that on some segments, my grandfather and Roscoe inherited the same segment of DNA from their parents, because today, my mother gave me that exact same segment that I share with both Don and Cheryl. Those segments are exactly identical and shown in the black boxes.

The only way for us to share this DNA today is for us to have shared a common ancestor who gave it to two of their children who passed it on to their descendants who DNA tested today.

On other segments, in red boxes, I share part of the same segments of DNA with Cheryl and Don, but someone along the line didn’t inherit all of that segment. For example on chromosome 3, in the red box, you can see that I share more with Cheryl (blue) than Don (red.)

In other cases, I share with either Don or Cheryl, but Don and Cheryl didn’t inherit that same segment of DNA from their father, so I don’t share with both of them. Those are the areas where you see only blue or only red.

On chromosome 12, you can see where it looks like Don’s and Cheryl’s segments butt up against each other. The DNA was clearly divided there. Don received one piece and Cheryl got the other. That’s known as a crossover and you can read about crossovers here, if you’d like.

It’s important to be able to view segment information to be able to see how others match in order to identify which common ancestor that DNA came from.

In Common With

You can use the “In Common With” tool to see who you match in common with any match. My first 6 matches in common with Cheryl are shown below. Note that they are already all bucketed to my maternal side.

First Steps Family Tree DNA in common with

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You can click on up to 7 individuals in the check box at left to show them on the chromosome browser at once to see if they match you on common segments.

Each matching segment has its own history and may descend from a different ancestor in your common tree.

First Steps 7 match chromosome browser

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If combinations of people do match me on a common segment, because these matches are all on my maternal side, they are triangulated and we know they have to descend from a common ancestor, assuming the segment is large enough. You can read about the concept of triangulation here. Triangulation occurs when 3 or more people (who aren’t extremely closely related like parents or siblings) all match each other on the same reasonably sized segment of DNA.

If you want to download your matches and work through this process in a spreadsheet, that’s an option too.

Size Matters

Small segments can be identical by chance instead of identical by descent.

  • “Identical by chance” means that you accidentally match someone because your DNA on that segment has been combined from both parents and causes it to match another person, making the segment “looks like” it comes from a common ancestor, when it really doesn’t. When DNA is sequenced, both your mother and father’s strands are sequenced, meaning that there’s no way to determine which came from whom. Think of a street with Mom’s side and Dad’s side with identical addresses on the houses on both sides. I wrote about that here.
  • “Identical by descent” means that the DNA is identical because it actually descends from a common ancestor. I discussed that concept in the article, We Match, But Are We Related.

Generally, we only utilize 7cM (centiMorgan) segments and above because at that level, about half of the segments are identical by descent and about half are identical by chance, known as false positives. By the time we move above 15 cM, most, but not all, matches are legitimate. You can read about segment size and accuracy here.

Using “In Common With” and the Matrix

“In Common With” is about who shares DNA. You can select someone you match to see who else you BOTH match. Just because you match two other people doesn’t necessarily mean that it’s on the same segment of DNA. In fact, you could match one person from your mother’s side and the other person from your father’s side.

First Steps match matrix.png

In this example, you match Person B due to ancestor John Doe and Person C due to ancestor Susie Smith. However, Person B also matches person C, but due to ancestor William West that they share and you don’t.

This example shows you THAT they match, but not HOW they match.

The only way to assure that the matches between the three people above are due to the same ancestor is to look at the segments with a chromosome browser and compare all 3 people to each other. Finding 3 people who match on the same segment, from the same side of your tree means that (assuming a reasonably large segment) you share a common ancestor.

Family Tree DNA has a nice matrix function that allows you to see which of your matches also match each other.

First steps matrix link

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The important distinction between the matrix and the chromosome browser is that the chromosome browser shows you where your matches match you, but those matches could be from both sides of your tree, unless they are bucketed. The matrix shows you if your matches also match each other, which is a huge clue that they are probably from the same side of your tree.

First Steps Family Tree DNA matrix.png

A matrix match is a significant clue in terms of who descends from which ancestors. For example, I know, based on who Amy matches, and who she doesn’t match, that she descends from the Ferverda side and that Charles, Rex and Maxine descend from ancestors on the Miller side.

Looking in the chromosome browser, I can tell that Cheryl, Don, Amy and I match on some common segments.

Matching multiple people on the same segment that descends from a common ancestor is called triangulation.

Let’s take a look at the MyHeritage triangulation tool.

MyHeritage

Moving now to MyHeritage who provides us with an easy to use triangulation tool, we see the following when clicking on DNA matches on the DNA tab on the toolbar.

First Steps MyHeritage matches

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Cousin Cheryl is at MyHeritage too. By clicking on Review DNA Match, the purple button on the right, I can see who else I match in common with Cheryl, plus triangulation.

The list of people Cheryl and I both match is shown below, along with our relationships to each person.

First Steps MyHeritage triangulation

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I’ve selected 2 matches to illustrate.

The first match has a little purple icon to the right which means that Amy triangulates with me and Cheryl.

The second match, Rex, means that while we both match Rex, it’s not on the same segment. I know that without looking further because there is no triangulation button. We both match Rex, but Cheryl matches Rex on a different segment than I do.

Without additional genealogy work, using DNA alone, I can’t say whether or not Cheryl, Rex and I all share a common ancestor. As it turns out, we do. Rex is a known cousin who I tested. However, in an unknown situation, I would have to view the trees of those matches to make that determination.

Triangulation

Clicking on the purple triangulation icon for Amy shows me the segments that all 3 of us, me, Amy and Cheryl share in common as compared to me.

First Steps MyHeritage triangulation chromosome browser.png

Cheryl is red and Amy is yellow. The one segment bracketed with the rounded rectangle is the segment shared by all 3 of us.

Do we have a common ancestor? I know Cheryl and I do, but maybe I don’t know who Amy is. Let’s look at Amy’s tree which is also shown if I scroll down.

First Steps MyHeritage common ancestor.png

Amy didn’t have her tree built out far enough to show our common ancestor, but I immediately recognized the surname Ferveda found in her tree a couple of generations back. Darlene was the daughter of Donald Ferverda who was the son of Hiram Ferverda, my great-grandfather.

Hiram was the father of Cheryl’s father, Roscoe and my grandfather, John Ferverda.

First Steps Hiram Ferverda pedigree.png

Amy is my first cousin twice removed and that segment of DNA that I share with her is from either Hiram Ferverda or his wife Eva Miller.

Now, based on who else Amy matches, I can probably tell whether that segment descends from Hiram or Eva.

Viva triangulation!

Theory of Family Relativity

MyHeritage’s Theory of Family Relativity provides theories to people whose DNA matches regarding their common ancestor if MyHeritage can calculate how the 2 people are potentially related.

MyHeritage uses a combination of tools to make that connection, including:

  • DNA matches
  • Your tree
  • Your match’s tree
  • Other people’s trees at MyHeritage, FamilySearch and Geni if the common ancestor cannot be found in your tree compared against your DNA match’s MyHeritage
  • Documents in the MyHeritage data collection, such as census records, for example.

MyHeritage theory update

To view the Theories, click on the purple “View Theories” banner or “View theory” under the DNA match.

First Steps MyHeritage theory of relativity

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The theory is displayed in summary format first.

MyHeritage view full theory

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You can click on the “View Full Theory” to see the detail and sources about how MyHeritage calculated various paths. I have up to 5 different theories that utilize separate resources.

MyHeritage review match

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A wonderful aspect of this feature is that MyHeritage shows you exactly the information they utilized and calculates a confidence factor as well.

All theories should be viewed as exactly that and should be evaluated critically for accuracy, taking into consideration sources and documentation.

I wrote about using Theories of Relativity, with instructions, here and here.

I love this tool and find the Theories mostly accurate.

AncestryDNA

Ancestry doesn’t offer a chromosome browser or triangulation but does offer a tree view for people that you match, so long as you have a subscription. In the past, a special “Light” subscription for DNA only was available for approximately $49 per year that provided access to the trees of your DNA matches and other DNA-related features. You could not order online and had to call support, sometimes asking for a supervisor in order to purchase that reduced-cost subscription. The “Light” subscription did not provide access to anything outside of DNA results, meaning documents, etc. I don’t know if this is still available.

After signing on, click on DNA matches on the DNA tab on the toolbar.

You’ll see the following match list.

First Steps Ancestry matches

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I’ve tested twice at Ancestry, the second time when they moved to their new chip, so I’m my own highest match. Click on any match name to view more.

First Steps Ancestry shared matches

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You’ll see information about common ancestors if you have some in your trees, plus the amount of shared DNA along with a link to Shared Matches.

I found one of the same cousins at Ancestry whose match we were viewing at MyHeritage, so let’s see what her match to me at Ancestry looks like.

Below are my shared matches with that cousin. The notes to the right are mine, not provided by Ancestry. I make extensive use of the notes fields provided by the vendors.

First Steps Ancestry shared matches with cousin

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On your match list, you can click on any match, then on Shared Matches to see who you both match in common. While Ancestry provides no chromosome browser, you can see the amount of DNA that you share and trees, if any exist.

Let’s look at a tree comparison when a common ancestor can be detected in a tree within the past 7 generations.

First Steps Ancestry view ThruLines.png

What’s missing of course is that I can’t see how we match because there’s no chromosome browser, nor can I see if my matches match each other.

Stitched Trees

What I can see, if I click on “View ThruLines” above or ThruLines on the DNA Summary page on the main DNA tab is all of the people I match who Ancestry THINKS we descend from a common ancestor. This ancestor information isn’t always taken from either person’s tree.

For example, if my match hadn’t included Hiram Ferverda in her tree, Ancestry would use other people’s trees to “stitch them together” such that the tester is shown to be descended from a common ancestor with me. Sometimes these stitched trees are accurate and sometimes they are not, although they have improved since they were first released. I wrote about ThruLines here.

First Steps Ancestry ThruLines tree

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In closer generations, especially if you are looking to connect with cousins, tree matching is a very valuable tool. In the graphic above, you can see all of the cousins who descend from Hiram Ferverda who have tested and DNA match to me. These DNA matches to me either descend from Hiram according to their trees, or Ancestry believes they descend from Hiram based on other people’s trees.

With more distant ancestors, other people’s trees are increasingly likely to be copied with no sources, so take them with a very large grain of salt (perchance the entire salt lick.) I use ThruLines as hints, not gospel, especially the further back in time the common ancestor. I wish they reached back another couple of generations. They are great hints and they end with the 7th generation where my brick walls tend to begin!

23andMe

I haven’t mentioned 23andMe yet in this article. Genealogists do test there, especially adoptees who need to fish in every pond.

23andMe is often the 4th choice of the major 4 vendors for genealogy due to the following challenges:

  • No tree support, other than allowing you to link to a tree at FamilySearch or elsewhere. This means no tree matching.
  • Less than 2000 matches, meaning that every person is limited to a maximum of 2000 matches, minus however many of those 2000 don’t opt-in for genealogical matching. Given that 23andMe’s focus is increasingly health, my number of matches continues to decrease and is currently just over 1500. The good news is that those 1500 are my highest, meaning closest matches. The bad news is the genealogy is not 23andMe’s focus.

If you are an adoptee, a die-hard genealogist or specifically interested in ethnicity, then test at 23andMe. Otherwise all three of the other vendors would be better choices.

However, like the other vendors, 23andMe does have some features that are unique.

Their ethnicity predictions are acknowledged to be excellent. Ethnicity at 23andMe is called Ancestry Composition, and you’ll see that immediately when you sign in to your account.

First Steps 23andMe DNA Relatives.png

Your matches at 23andMe are found under DNA Relatives.

First Steps 23andMe tools

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At left, you’ll find filters and the search box.

Mom’s and Dad’s side filter matches if you’ve tested your parents, but it’s not like the Family Tree DNA bucketing that provides maternal and paternal side bucketing by utilizing through third cousins if your parents aren’t available for testing.

Family names aren’t your family names, but the top family names that match to you. Guess what my highest name is? Smith.

However, Ancestor Birthplaces are quite useful because you can sort by country. For example, my mother’s grandfather Ferverda was born in the Netherlands.

First Steps 23andMe country.png

If I click on Netherlands, I can see my 5 matches with ancestors born in the Netherlands. Of course, this doesn’t mean that I match because of my match’s Dutch ancestors, but it does provide me with a place to look for a common ancestor and I can proceed by seeing who I match in common with those matches. Unfortunately, without trees we’re left to rely on ancestor birthplaces and family surnames, if my matches have entered that information.

One of my Dutch matches also matches my Ferverda cousin. Given that connection, and that the Ferverda family immigrated from Holland in 1868, that’s a starting point.

MyHeritage has a similar features and they are much more prevalent in Europe.

By clicking on my Ferverda cousin, I can view the DNA we share, who we match in common, our common ethnicity and more. I have the option of comparing multiple people in the chromosome browser by clicking on “View DNA Comparison” and then selecting who I wish to compare.

First Steps 23andMe view DNA Comparison.png

By scrolling down instead of clicking on View DNA Comparison, I can view where my Ferverda cousin matches me on my chromosomes, shown below.

First STeps 23andMe chromosome browser.png

23andMe identifies completely identical segments which would be painted in dark purple, the legend at bottom left.

Adoptees love this feature because it would immediately differentiate between half and full siblings. Full siblings share approximately 25% of the exact DNA on both their maternal and paternal strands of DNA, while half siblings only share the DNA from one parent – assuming their parents aren’t closely related. I share no completely identical DNA with my Ferverda cousin, so no segments are painted dark purple.

23andMe and Ancestry Maps Show Where Your Matches Live

Another reason that adoptees and people searching for birth parents or unknown relatives like 23andMe is because of the map function.

After clicking on DNA Relatives, click on the Map function at the top of the page which displays the following map.

First Steps 23andMe map

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This isn’t a map of where your matches ancestors lived, but is where your matches THEMSELVES live. Furthermore, you can zoom in, click on the button and it displays the name of the individual and the city where they live or whatever they entered in the location field.

First Steps 23andMe your location on map.png

I entered a location in my profile and confirmed that the location indeed displays on my match’s maps by signing on to another family member’s account. What I saw is the display above. I’d wager that most testers don’t realize that their home location and photo, if entered, is being displayed to their matches.

I think sharing my ancestors’ locations is a wonderful, helpful, idea, but there is absolutely no reason whatsoever for anyone to know where I live and I feel it’s stalker-creepy and a safety risk.

First Steps 23andMe questions.png

If you enter a location in this field in your profile, it displays on the map.

If you test with 23andMe and you don’t want your location to display on this map to your matches, don’t answer any question that asks you where you call home or anything similar. I never answer any questions at 23andMe. They are known for asking you the same question repeatedly, in multiple locations and ways, until you relent and answer.

Ancestry has a similar map feature and they’ve also begun to ask you questions that are unrelated to genealogy.

Ancestry Map Shows Where Your Matches Live

At Ancestry, when you click to see your DNA matches, look to the right at the map link.

First Steps Ancestry map link.png

By clicking on this link, you can see the locations that people have entered into their profile.

First Steps Ancestry match map.png

As you can see, above, I don’t have a location entered and I am prompted for one. Note that Ancestry does specifically say that this location will be shown to your matches.

You can click on the Ancestry Profile link here, or go to your Personal Profile by click the dropdown under your user name in the upper right hand corner of any page.

This is important because if you DON’T want your location to show, you need to be sure there is nothing entered in the location field.

First Steps Ancestry profile.png

Under your profile, click “Edit.”

First Steps Ancestry edit profile.png

After clicking edit, complete the information you wish to have public or remove the information you do not.

First Steps Ancestry location in profile.png

Sometimes Your Answer is a Little More Complicated

This is a First Steps article. Sometimes the answer you seek might be a little more complicated. That’s why there are specialists who deal with this all day, everyday.

What issues might be more complex?

If you’re just starting out, don’t worry about these things for now. Just know when you run into something more complex or that doesn’t make sense, I’m here and so are others. Here’s a link to my Help page.

Getting Started

What do you need to get started?

  • You need to take a DNA test, or more specifically, multiple DNA tests. You can test at Ancestry or 23andMe and transfer your results to both Family Tree DNA and MyHeritage, or you can test directly at all vendors.

Neither Ancestry nor 23andMe accept uploads, meaning other vendors tests, but both MyHeritage and Family Tree DNA accept most file versions. Instructions for how to download and upload your DNA results are found below, by vendor:

Both MyHeritage and Family Tree DNA charge a minimal fee to unlock their advanced features such as chromosome browsers and ethnicity if you upload transfer files, but it’s less costly in both cases than testing directly. However, if you want the MyHeritage DNA plus Health or the Family Tree DNA Y DNA or Mitochondrial DNA tests, you must test directly at those companies for those tests.

  • It’s not required, but it would be in your best interest to build as much of a tree at all three vendors as you can. Every little bit helps.

Your first tree-building step should be to record what your family knows about your grandparents and great-grandparents, aunts and uncles. Here’s what my first step attempt looked like. It’s cringe-worthy now, but everyone has to start someplace. Just do it!

You can build a tree at either Ancestry or MyHeritage and download your tree for uploading at the other vendors. Or, you can build the tree using genealogy software on your computer and upload to all 3 places. I maintain my primary tree on my computer using RootsMagic. There are many options. MyHeritage even provides free tree builder software.

Both Ancestry and MyHeritage offer research/data subscriptions that provide you with hints to historical documents that increase what you know about your ancestors. The MyHeritage subscription can be tried for free. I have full subscriptions to both Ancestry and MyHeritage because they both include documents in their collections that the other does not.

Please be aware that document suggestions are hints and each one needs to be evaluated in the context of what you know and what’s reasonable. For example, if your ancestor was born in 1750, they are not included in the 1900 census, nor do women have children at age 70. People do have exactly the same names. FindAGrave information is entered by humans and is not always accurate. Just sayin’…

Evaluate critically and skeptically.

Ok, Let’s Go!

When your DNA results are ready, sign on to each vendor, look at your matches and use this article to begin to feel your way around. It’s exciting and the promise is immense. Feel free to share the link to this article on social media or with anyone else who might need help.

You are the cumulative product of your ancestors. What better way to get to know them than through their DNA that’s shared between you and your cousins!

What can you discover today?

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Disclosure

I receive a small contribution when you click on some of the links to vendors in my articles. This does NOT increase the price you pay but helps me to keep the lights on and this informational blog free for everyone. Please click on the links in the articles or to the vendors below if you are purchasing products or DNA testing.

Thank you so much.

DNA Purchases and Free Transfers

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Full or Half Siblings?

Many people are receiving unexpected sibling matches. Everyday on social media, “surprises” are being reported so often that they are no longer surprising – unless of course you’re the people directly involved and then it’s very personal, life-altering and you’re in shock. Staring at a computer screen in stunned disbelief.

Conversely, sometimes that surprise involves people we already know, love and believe to be full siblings – but autosomal DNA testing casts doubt.

If your sibling doesn’t match at all, download your DNA files and upload to another company to verify. This step can be done quickly.

Often people will retest, from scratch, with another company just for the peace of mind of confirming that a sample didn’t get swapped. If a sample was swapped, then another unknown person will match you at the sibling level, because they would be the one with your sibling’s kit. It’s extremely rare, but it has happened.

If the two siblings aren’t biologically related at all, we need to consider that one or both might have been adopted, but if the siblings do match but are predicted as half siblings, the cold fingers of panic wrap themselves around your heart because the ramifications are immediately obvious.

Your full sibling might not be your full sibling. But how can you tell? For sure? Especially when minutes seem like an eternity and your thoughts are riveted on finding the answer.

This article focuses on two tools to resolve the question of half versus full siblingship, plus a third safeguard.

Half Siblings Versus Step-Siblings

For purposes of clarification, a half sibling is a sibling you share only one parent with, while a step-sibling is your step-parent’s child from a relationship with someone other than your parent. Your step-parent marries your parent but is not your parent. You are not genetically related to your step-siblings unless your parent is related to your step-parent.

Parental Testing

Ideally two people who would like to know if they are full or half siblings would have both parents, or both “assumed” parents to compare their results with. However, life is seldom ideal and parents aren’t always available. Not to mention that parents in a situation where there was some doubt might be reluctant to test.

Furthermore, you may elect NOT to have your parents test if your test with your sibling casts doubt on the biological connections within your family. Think long and hard before exposing family secrets that may devastate people and potentially destroy existing relationships. However, this article is about the science of confirming full versus half siblings, not the ethics of what to do with that information. Let your conscience be your guide, because there is no “undo” button.

Ranges Aren’t Perfect

The good news is that autosomal DNA testing gives us the ability to tell full from half-siblings by comparing the siblings to each other, without any parent’s involvement.

Before we have this discussion, let me be very clear that we are NOT talking about using these tools to attempt to discern a relationship between two more distant unknown people. This is only for people who know, or think they know or suspect themselves to be either full or half siblings.

Why?

Because the ranges of the amount of DNA found in people sharing close family relationships varies and can overlap. In other words, different degrees of relationships can be expected to share the same amounts of DNA. Furthermore, except for parents with whom you share exactly 50% of your autosomal DNA (except males don’t share their father’s X chromosome), there is no hard and fast amount of DNA that you share with any relative. It varies and sometimes rather dramatically.

The first few lines of this Relationship Chart, from the 2016 article Concepts – Relationship Predictions, shows both first and second degree relationships (far right column).

Sibling shared cM chart 2016.png

You can see that first degree relations can be parent/child, or full siblings. Second degree relationships can be half siblings, grandparents, aunt/uncle or niece/nephew.

Today’s article is not about how to discern an unknown relation with someone, but how to determine ONLY if two people are half or full siblings to each other. In other words, we’re only trying to discern between rows two and three, above.

As more data was submitted to Blaine Bettinger’s Shared cM Project, the ranges changed as we continued to learn. Blaine’s 2017 results were combined into a useful visual tool at DNAPainter, showing various relationships.

Sibling shared cM DNAPainter.png

Note that in the 2017 version of the Shared cM Project, the high end of the half sibling range of 2312 overlaps with the low end of the full sibling range of 2209 – and that’s before we consider that the people involved might actually be statistical outliers. Outliers, by their very definition are rare, but they do occur. I have seen them, but not often. Blaine wrote about outliers here and here.

Full or Half Siblings?

So, how to we tell the difference, genetically, between full and half siblings?

There are two parts to this equation, plus an optional third safeguard:

  1. Total number of shared cM (centiMorgans)
  2. Fully Identical Regions (FIR) versus Half Identical Regions (HIR)

You can generally get a good idea just from the first part of the equation, but if there is any question, I prefer to download the results to GedMatch so I can confirm using the second part of the equation too.

The answer to this question is NOT something you want to be wrong about.

Total Number of Shared cM

Each child inherits half of each parent’s DNA, but not the same half. Therefore, full siblings will share approximately 50% of the same DNA, and half siblings will share approximately 25% when compared to each other.

You can see the differences on these charts where percentages are converted into cM (centiMorgans) and on the 2017 combined chart here.

I’ve summarized full and half siblings’ shared cMs of DNA from the 2017 chart, below.

Relationship Average Shared cM Range of Shared cM
Half Siblings 1,783 1,317 – 2,312
Full Siblings 2,629 2,209 – 3,394

Fully Identical and Half Identical Regions

Part of the DNA that full siblings inherit will be the exact same DNA from Mom and Dad, meaning that the siblings will match at the same location on their DNA on both Mom’s strand of DNA and Dad’s strand of DNA. These sections are called Fully Identical Regions, or FIR.

Half siblings won’t fully match, except for very small slivers where the nucleotides just happen to be the same (identical by chance) and that will only be for very short segments.

Half siblings will match each other, but only one parent’s side, called Half Identical Regions or HIR.

Roughly, we expect to see about 25% of the DNA of full siblings be fully identical, which means roughly half of their shared DNA is inherited identically from both parents.

Understanding the Concept of Half Identical Versus Fully Identical

To help understand this concept, every person has two strands of DNA, one from each parent. Think of two sides of a street but with the same addresses on both sides. A segment can “live” from 100-150 Main Street, er, I mean chromosome 1 – but you can’t tell just from the address if it’s on Mom’s side of the street or Dad’s.

However, when you match other people, you’ll be able to differentiate which side is which based on family members from that line and who you match in common with your sibling. This an example of why it’s so important to have close family members test.

Any one segment on either strand being compared between between full siblings can:

  • Not match at all, meaning the siblings inherited different DNA from both parents at this location
  • Match on one strand but not the other, meaning the siblings inherited the same DNA from one parent, but different DNA from the other. (Half identical.)
  • Match identically on both, meaning the siblings inherited exactly the same DNA in that location from both parents. (Fully identical.)

I created this chart to show this concept visually, reflecting the random “heads and tails” combination of DNA segments by comparing 4 sets of full siblings with one another.

Sibling full vs half 8 siblings arrows

This chart illustrates the concept of matching where siblings share:

  • No DNA on this segment (red arrow for child 1 and 2, for example)
  • Half identical regions (HIR) where siblings share the DNA from one parent OR the other (green arrow for child 1 and 2, for example, where the siblings share brown from mother)
  • Fully identical regions (FIR) where they share the same segment from BOTH parents so their DNA matches exactly on both strands (black boxed regions)

If a region isn’t either half or fully identical, it means the siblings don’t match on that piece of DNA at all. That’s to be expected in roughly 50% of the time for full siblings, and 75% of the time for half siblings. That’s no problem, unless the siblings don’t match at all, and that’s entirely different, of course.

Let’s look at how the various vendors address half versus full siblings and what tools we have to determine which is which.

Ancestry

Ancestry predicts a relationship range and provides the amount of shared DNA, but offers no tools for customers to differentiate between half versus full siblings. Ancestry has no chromosome browser to facilitate viewing DNA matches but shared matches can sometimes be useful, especially if other close family members have tested.

Sibling Ancestry.png

Update 4-4-2019 – I was contacted by a colleague who works for an Ancestry company, who provided this information: Ancestry is using “Close Family” to designate avuncular, grandparent/grandchild and half-sibling relationships. If you see “Immediate Family “the relationship is a full sibling.

Customers are not able to view the results for ourselves, but according to my colleague, Ancestry is using FIRs and HIRs behind the scenes to make this designation. The Ancestry Matching White Paper is here, dating from 2016.

If Ancestry changes their current labeling in the future, this may not longer be exactly accurate. Hopefully new labeling would provide more clarity. The good news is that you can verify for yourself at GedMatch.

A big thank you to my colleague!

MyHeritage

MyHeritage provides estimated relationships, a chromosome browser and the amount of shared DNA along with triangulation but no specific tool to determine whether another tester is a full or half sibling. One clue can be if one of the siblings has a proven second cousin or closer match that is absent for the other sibling, meaning the siblings and the second cousin (or closer) do not all match with each other.

Sibling MyHeritage.png

Family Tree DNA

At Family Tree DNA, you can see the amount of shared DNA. They also they predict a relationship range, include a chromosome browser, in common matching and family phasing, also called bucketing which sorts your matches into maternal and paternal sides. They offer additional Y DNA testing which can be extremely useful for males.

Sibling FamilyTreeDNA.png

If the two siblings in question are male, a Y DNA test will shed light on the question of whether or not they share the same father (unless the two fathers are half brothers or otherwise closely related on the direct paternal line).

Sibling advanced matches.png

FamilyTreeDNA provides Advanced Matching tools that facilitate combined matching between Y and autosomal DNA.

Sibling bucketing both.png

FamilyTreeDNA’s Family Finder maternal/paternal bucketing tool is helpful because full siblings should be assigned to “both” parents, shown in purple, not just one parent, assuming any third cousins or closer have tested on both sides, or at least on the side in question.

As you can see, on the test above, the tester matches her sister at a level that could be either a high half sibling match, or a low full sibling match. In this case, it’s a full sibling, not only because both parents tested and she matched, but because even before her parents tested, she was already bucketed to both sides based on cousins who had tested on both the maternal and paternal sides of the family.

GedMatch

GedMatch, an upload site, shows the amount of shared DNA as well. Select the One-to-One matching and the “Graph and Position” option, letting the rest of the settings default.

Sibling GedMatch menu.png

GedMatch doesn’t provide predicted relationship ranges as such, but instead estimates the number of generations to the most recent common ancestor – in this case, the parents.

Sibling GedMatch total.png

However, GedMatch does offer an important feature through their chromosome browser that shows fully identical regions.

To illustrate, first, I’m showing two kits below that are known to be full siblings.

The green areas are FIR or Fully Identical Regions which are easy to spot because of the bright green coloring. Yellow indicate half identical matching regions and red means there is no match.

Sibling GedMatch legend.png

Please note that this legend varies slightly between the legacy GedMatch and GedMatch Genesis, but yellow, green, purple and red thankfully remain the same. The blue base indicates an entire region that matches, while the grey indicates an entire region not considered a match..

Sibling GedMatch FIR.png

Fully identical green regions (FIR) above are easy to differentiate when compared with half siblings who share only half identical regions (HIR).

The second example, below, shows two half-siblings that share one parent.

Sibling GedMatch HIR.png

As you can see, there are slivers of green where the nucleotides that both parents contributed to the respective children just happen to be the same for a very short distance on each chromosome. Compared to the full sibling chart, the green looks very different.

The half-sibling small green segments are fully identical by chance or by population, but not identical by descent which would mean the segments are identical because the individuals share both parents. These two people don’t share both parents.

The fully identical regions for full siblings are much more pronounced, in addition to full siblings generally sharing more total DNA.

GedMatch is the easiest and most useful site to work with for determining half versus full siblings by comparing HIR/FIR. I wrote instructions for downloading your DNA from each of the testing vendors at the links below:

Twins

Fraternal twins are the same as regular siblings. They share the same space for 9 months but are genetically siblings. Identical twins, on the other hand, are nearly impossible to tell apart genetically, and for all intents and purposes cannot be distinguished in this type of testing.

Sibling GedMatch identical twin.png

Here’s the same chart for identical twins.

23andMe

23andMe also provides relationship estimates, along with the amount of shared DNA, a chromosome browser that includes triangulation (although they don’t call it that) and a tool to identify full versus half identical regions. 23andMe does not support trees, a critical tool for genealogists.

Unfortunately, 23andMe has become the “last” company that people use for genealogy. Most of their testers seem to be seeking health information today.

If you just happen to have already tested at 23andMe with your siblings, great, because you can use these tools. If you have not tested at 23andMe, simply upload your results from any vendor to GedMatch.

At 23andMe, under the Ancestry, then DNA Relatives tabs, click on your sibling’s match to view genetic information, assuming you both have opted into matching. If you don’t match your sibling, PLEASE be sure you BOTH have completely opted in for matching. I can’t tell you how many panic stricken siblings I’ve coached who weren’t both opted in to matching. If you’re experiencing difficulty, don’t panic. Simply download both people’s files to GedMatch for an easier comparison. You can find 23andMe download instructions here.

Sibling 23andMe HIR.png

Scrolling down, you can see the options for both half and completely identical segments on your chromosomes as compared to your match. Above,  my child matches me completely on half identical regions. This makes perfect sense, of course, because my father and my child’s father are not the same person and are not related.

Conversely, this next match is my identical twin whom I match completely identically on all segments.

Sibling 23andMe FIR.png

Confession – I don’t have an identical twin. This is actually my V3 test compared with my V4 test, but these two tests are in essence identical twin tests.

Unusual Circumstances

The combination of these two tools, DNA matching and half versus fully identical regions generally provides a relatively conclusive answer as to whether two individuals are half or full siblings. Note the words generally and relatively.

There are circumstances that aren’t as clear cut, such as when the father of the second child is a brother or other close relative of the first child’s father – assuming that both children share the same mother. These people are sometimes called three quarters siblings or niblings.

In other situations, the parents are related, sometimes closely, complicating the genetics.

These cases tend to be quite messy and should be unraveled with the help of a professional. I recommend www.dnaadoption.com (free unknown parent search specialists) or Legacy Tree Genealogists (professional genealogists.)

The Final SafeGuard – Just in Case

A third check, should any doubt remain about full versus half siblings, would be to find a relative that is a second cousin or closer on the presumed mother’s side and one on the presumed father’s side, and compare autosomal results of both relatives to both siblings.

There has never been a documented case of second cousins or closer NOT matching each other. I’m unclear about second cousins once removed, or half second cousins, but about 10% of third cousins don’t match. To date, second cousins (or closer) who didn’t match, didn’t match because they weren’t really biological second cousins.

If the two children are full siblings meaning the biological children of both the presumed parents, both siblings will match the 2nd cousin or closer on the mother’s side AND the 2nd cousin or closer on the father’s side as well. If they are not full siblings, one will match only on the second cousin on the common parent’s side.

You can see in the example below that Child 1 and Child 2, full siblings, match both Hezekiah (green), a second cousin from the father’s side, as well as Susan (pink), a second cousin from the mother’s side.

Sibling both sides matching.png

If one of the two children only matches one cousin, and not the other, then the person who doesn’t match the cousin from the father’s side, for example, is not related to the father – although depending on the distance of the relationship, I would seek an additional cousin to test through a different child – just in case.

You can see in the example below that Child 2 matches both Hezekiah (green) and Susan (pink), but Child 1 only matches Susan (pink), from the mother’s side, meaning that Child 1 does not descend from John, so isn’t the child of the Presumed Father (green).
Sibling both sides not matching.png

If neither child matches Hezekiah, that’s a different story. You need to consider the possibility of one of the following:

  • Neither child is the child of the Presumed Father, and could potentially be fathered by different men
  • A break occurred in the genetic line someplace between John and Hezekiah or between John and the Presumed Father.

In other words, the only way this safeguard works as a final check is if at least ONE of the children matches both presumed parents’ lines with a second cousin or closer.

And yes, these types of “biological lineage disruptions” do occur and much more frequently that first believed.

In the End

You may not need this safeguard check when the first and second methodologies, separately or together, are relatively conclusive. Sometimes these decisions about half versus full siblings incorporate non-genetic situational information, but be careful about tainting your scientific information with confirmation bias – meaning unintentionally skewing the information to produce the result that you might desperately want.

When I’m working with a question as emotionally loaded as trying to determine whether people are half or full siblings, I want every extra check and safeguard available – and you will too. I utilize every tool at my disposal so that I don’t inadvertently draw the wrong conclusion.

I want to make sure I’ve looked under every possible rock for evidence. I try to disprove as much as I try to prove. The question of full versus half siblingship is one of the most common topics of the Quick Consults that I offer. Even when people think they know the answer, it’s not uncommon to ask an expert to take a look to confirm. It’s a very emotional topic and sometimes we are just too close to the subject to be rational and objective.

Regardless of the genetic outcome, I hope that you’ll remember that your siblings are your siblings, your parents are your parents (genetic or otherwise) and love is love – regardless of biology. Please don’t lose the compassionate, human aspect of genealogy in the fervor of the hunt.

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