Things That Need To Be Said: Adoption, Adultery, Coercion, Rape and DNA

doesn't add up

What happens when DNA results don’t add up?

Recently I wrote about how to distinguish genetically if two people are full or half siblings. Sometimes people who thought they were full siblings turn out only to be half siblings, and it’s a painful discovery.

What do people immediately assume when a father turns out not to be who he’s expected to be?

What’s the first thought that jumped into your head?

Somebody was cheating, yes?!!

And that somebody was obviously the female who became pregnant, right?

Now she’s caught thanks to DNA.

Hold on.

Not so fast.

Mis-attributed Parentage

I’ve seen a lot of discussion recently about NPEs, Non-Parental Events, also known as mis-attributed paternity (MPE,) undocumented adoptions and probably other terms too.

In essence, when the expected father turns out not to be the biological father. I suspect that the uptick in discussion is a direct result of the significant number of people DNA testing today.

For the most part, when there were few autosomal testers, unless someone failed to match against the known close family members who had already tested, the situation remained largely undiscovered.

However, today with more and more testers, it’s common for people to have several close matches, which makes the absence of a first or second cousin, aunt, uncle, sibling or parent match stand out like a sore thumb – throbbing painfully and demanding answers.

And of course, when a child and parent don’t match, it’s immediately evident to all parties concerned. And, it’s excruciating.

When DNA test results arrive and reveal unexpected surprises, it can be quite uncomfortable and will throw your world into a tailspin. And that’s, um, let’s just say putting it mildly.

It’s disconcerting enough when you don’t match to a couple – which implies an adoption of some sort. When you match half of the couple, that’s a horse of a different color.

Typically, a half match will mean that you match the female’s side of the family, but not the male’s.

It’s particularly difficult when a father or grandfather is not who the family believes that person to be. You probably knew them and if not, other family members did.

The first thing that springs to mind is that someone was “cheating” on their spouse. And that someone was your mother or grandmother – another person you know and love.

To make matters even more awkward, one or both of the couple involved may still be living.

Infidelity

Infidelity is probably not the first thing that should be considered in situations like these. Let’s look at this from the other perspective. How might this have happened if the female wasn’t unfaithful?

I’ve worked with genetic genealogy cases, including these types of surprises for 19 years now, and the truth is sometimes quite different.

Aside from infidelity which is really the last possibility we should consider, there other scenarios that are at least as likely, in no particular order:

  • Infertility/sperm donation
  • Adoption, either legal (through the courts) or someone, possibly a family member, taking a child to raise
  • Sexual Assault – meaning rape
  • Coercion
  • Agreed-upon lifestyle

Furthermore, even if the event that led to the pregnancy was consensual, people can and do make what they later consider to be errors in judgement, especially when alcohol is involved. Anyone here never make a mistake? Didn’t think so.

Looking back, it’s difficult to be too harsh because you wouldn’t be who you are and your siblings wouldn’t be who they are if those long-ago events had unfolded differently. Our ancestors, including our parents, weren’t saints. Many women stayed in “bad” marriages which may have made an emotional respite look particularly attractive.

I try very hard to stay away from moral judgement without knowing the full story – and most of the time – that’s something we will never know for one of many reasons.

Let’s start out by looking at some potential reasons for a parental mismatch that don’t involve infidelity, meaning deception.

Infertility, Sperm Donation, Lifestyle and Adoption

Fertility issues have plagued couples ever since there have been couples. Adoption speaks for itself, but many adoptions were hidden from children and family members -and often remain so until a DNA result exposes the secret.

If the father that raised the person isn’t the biological father, the mother may or may not be the biological mother.

Some adoptions are uni-parental, meaning a step-father adopts the child. This happened often. Historically, this is especially prevalent in situations where the mother had the first child without being married and the family was attempting to protect both the mother and the child from the social condemnation and stigma of illegitimacy, or “bastardry” as it was called in the legal records at one time. It’s no wonder that no one talked about this and the situation was treated as a dark secret. Conversely, in some historical cases, I think that at the time “everyone knew,” but didn’t discuss it, and there was no reason to record the information.

However, when working with more contemporary adoption records, it may appear that both parents adopted the child, when in fact only one was not the biological parent. Michigan is one of those states. In order for the step-father to adopt a child, the mother must give up her parental rights and the couple adopts the child together. If you’re thinking this is going to play havoc with future genealogists, you’re right, it is.

Without that legal adoption information, genetically it “looks” like the mother is the mother, but the father isn’t the father – and a uni-parental adoption is NOT the first thing that comes to mind. Infidelity is.

If DNA results indicate that the mother is the mother but the man she was married to at the time is not the biological father, it’s certainly possible that sperm donation was utilized. The first successful pregnancy from frozen semen occurred in 1953, meaning the resulting children could be retirement age today.

Before “official” sperm donation, let’s just say that sometimes couples took care of the issue themselves, in the old-fashioned way. You may discover evidence of the result without understanding the situation. That’s just not something couples shared with other people for a wide variety of reasons – but I know of at least two separate situations where this occurred and was known within the immediate family. In one case, the mutually agreed upon “donor” was the man’s brother.

This also touches upon an open lifestyle situation – meaning that the couple agreed to have an non-monogamous sexual relationship of some form. “Key parties” in my parent’s generation are legendary – a form of adult spin-the-bottle. In my circle of friends, someone discovered this “recreational event” was occurring at their parents’ parties and let’s just say we teens discussed it endlessly. We vacillated between being horrified and entranced. Don’t expect to find grandma discussing this at the holiday table – but that doesn’t mean it didn’t happen.

Our ancestors were human too. Customs and taboos revolving around sexual relationships are cultural and vary by time and place. “Rules” are created by people, and people are always breaking the rules. Some things never change.

The above scenarios represent a range of perfectly legitimate reasons why a DNA result may not reflect the parent of record but don’t represent wrongdoing or betrayal by either party. It’s just that today, we don’t have that background information – our only view is through the genetic results and we have to infer the rest.

Of course, there are other much more unpleasant scenarios that need to be considered too.

Rape

Rape is pretty straightforward, or at least it seems so on the surface, but even rape may hold darker secrets. Rape can be a violent crime, meaning the “in the alley” type of rape where a woman doesn’t know her assailant. However, that’s not the most common rape scenario.

In the majority of cases the female knows her rapist. He might be a boyfriend, or even more disconcerting, a family member. And she may not have been old enough to consent, even if the assault wasn’t overtly violent.

She may never have “told” because of fear, misplaced shame, she didn’t think she would be believed or for fear that her situation would become worse, not better. She may also have been threatened, implicitly or explicitly.

She may have been too young or naïve to understand that while she was “seduced,” she was not responsible and she was not able at her young age to give consent. Many adult seducers tell their underage victims that they love them and if they tell, they will both get in trouble for their “love.” Often the seducer aka rapist inflicts guilt on the young female for “enjoying it.” Often the rapist will “treat” their victim to make them feel special. Oprah Winfrey’s rapist, her 19 year old cousin, bought 9 year old Oprah an ice cream cone afterwards.

If just reading these words makes you uncomfortable, welcome to a peek inside the world of being a victim.

Coercion

A middle ground is coercion, where the female doesn’t really have the ability to say no, or she was deceived or pressured into doing something she didn’t freely want, understand or consent to do.

The most poignant example I can think of is a slave woman. Could a slave realistically say “no”? If not, maybe she simply didn’t physically resist because resistance was futile and would only result in her being whipped as well. “Not resisting” under these circumstances is not at all the same as freely given consent.

I know women personally that have yielded or “agreed” to sexual relationships to keep their jobs, especially if they were raising children alone. That’s coercion, plain and simple, where one person holds power over the other. Most women (and some men) have experienced something similar.

In my own case, I refused the advances of an older male supervisor when I was in my 90-day probationary period at a well-paying civil service job (post office) when I was in college. The result is exactly what you might expect, I was let go before my 90 day probationary period ended.

Did I regret my decision? Not one bit, but I was also furious with no possible recourse. I did report the fact that the supervisor arrived uninvited and unwelcome at my home when my husband was working, along with his behavior, but of course, nothing at all was done – except me being punished by being let go. The supervisor denied everything. To be clear, I was not raped, but it was either “put out or lose your job.”

I was married with a child. I needed that job, but I was not entirely dependent on it for the family income. Not to mention, I’m incredibly tenacious (nice word for stubborn) and threatening me is exactly how NOT to get what you want.

What would have happened to an unmarried woman with a child who was entirely dependent on that job? This situation is not the exception and vulnerable women are often targeted and preyed upon.

Women also know and knew then that victims were often blamed, so women didn’t and don’t volunteer for a second humiliation on top of what has already happened. Justice is and was seldom served.

Pregnancy

I know these are uncomfortable thoughts and rape is an incredibly ugly word, but the conclusion that your ancestor, a woman you know and love, “cheated” shouldn’t be considered simply because it’s easier to ponder than the fact that she might have been raped, coerced or been intoxicated.

Setting aside the topic of rape and coercion for a minute, the reality is that women drank socially – our mothers and our grandmothers. Even being raised Baptist, I did and drank too much more than once.

Men/boys know/knew that a woman who had a few drinks was much easier to seduce that one that was stone cold sober. The mother and grandmother you knew years later may have been somewhat different than a younger version of that person. Children are often a driving motivation to “settle down.”

When sexual relationships occur that result in pregnancy, whether it’s consensual or not, it’s always the female who physically carries the evidence in an undeniable way, and the associated societal burden as well. How many times have you hear about “fallen women” but never about “fallen men.” The stigma is unfairly place on women, and often women alone. For example, men are forgiven for being drunk and no one even gives it a second thought, but women are cast as harlots – especially if they carry the evidence publicly by being pregnant and then having an illegitimate child. That evidence lasts forever and is a daily reminder for all who would condemn and shame her.

Retrospectively, we should never, ever assume that a female chose to “cheat” as the first presumption. If anything, it should be our last consideration.

We need to approach the memory of our ancestors, including our parents, with the presumption of innocence and an attitude of compassion. We also need to consider the distinct possibility of sexual assault. Rape.

Let’s Talk About Sexual Assault

The incidence of sexual assault is notoriously difficult to measure. Many times the shame or other surrounding circumstances prevent or highly discourage females from reporting rapes.

Before recent years when it was sometimes possible for a female to obtain work that paid enough to support herself and children, an unmarried or divorced woman was assured of both social rejection and devastating poverty.

To report a rape was to be ostracized from family, from church, and possibly from your spouse. People asked if you encouraged the rape or “asked for it,” perhaps by drinking or dressing “provocatively” – and what was deemed to be provocative varied with the culture and times.

1920s bathing suit

For example, this swimsuit was considered very provocative in the 1920s. Today, this outfit doesn’t even merit a second look in America, but in some parts of the world, women still can’t reveal their faces for fear of “provoking” men. In other words, if a man raped a woman who wore this outfit, it was HER fault for tempting him, not his fault for raping her.

Was this woman advertising that she wanted sex or “asking to be raped?” If she was advertising for sex, then why would a man even need to rape her? The logic fails here, but sometimes provocation is the justification for rape. That insulting to women and men both.

Victorian swimsuits

Here’s the google result for “provocative swimsuit in Victorian times.” While styles that are considered provocative have changed, the way women are perceived who would dare to be “provocative” hasn’t. There is no excuse for rape.

Full stop.

A Second Victimization

If you are raped and report the incident, you are interviewed (often by men) about the intimate details, asked if you enjoyed it and if you climaxed. The woman is always suspect.

Both spoken and unspoken words twice victimize the woman – then and now.

Until and unless you report the rape, no one but you and the rapist knows about the first victimization. After a woman reports a rape, everyone knows about the public humiliation – forever – that public humiliation and its aftereffects never go away. Once out of the bottle, that stinking genie is permanently affixed to the female. The males often go un-apprehended and when apprehended, only minimally punished. By way of example, hundreds of thousands of rape kits lay unprocessed in police departments around the country. Many have been misplaced and lost. If this doesn’t say, “We don’t care,” I don’t know what does.

In my own personal circle, a female child, and I mean a pre-teen, was blamed when her rapist lost his job in the school system as a result of her reporting the rape to the police and to the school. The rapist’s wife, amazingly, didn’t leave him, even though they had children the same age. It was widely known in the community that the rape had been reported. As a result, THE CHILD RAPE VICTIM WAS BLAMED by the rapist’s family and bullied by his and other children in the neighborhood and at school!

Then, to add insult to injury, the rapist wasn’t even convicted because the young victim became too terrified to testify after what happened to her at school, even though there was conclusive medical evidence. The rape victim’s family wound up selling their home and moving in order to protect the child from further damage.

If you think this is rare, it isn’t.

Another person told me about their step-father who raped them beginning when they were pre-kindergarten and continuing the entire time they were in grade school. He then began to rape his kindergarten age biological daughter as well. What did the mother do when the older child repeatedly told her what was happening? Nothing. Absolutely nothing.

This story isn’t rare either as I’ve personally heard various permutations from MANY women, not just one or two – although most are too embarrassed and humiliated even years later to discuss this topic with other than a trusted friend – if even then. I’m truly stunned at the overwhelming number of women (and some men) with horrible secrets like this in their past – and also at how they have survived and thrived in spite of what happened. Care to guess how many rapists of the many women who have shared their experiences with me were prosecuted? One. Just one.

It’s no wonder why adult women were and are very hesitant to come forth following sexual assault. A rape is humiliating and demeaning. The victim is physically forced into doing something they don’t want to do, don’t understand, or they are for some reason unable to consent to or refuse, such as being underage or drugged. They feel filthy and vile after the rapist is done with them. Unclean, unworthy. Sometimes the male thinks her humiliation is funny. Sometimes they take pictures and tell their friends, who think it’s funny too.

Rapists are seldom prosecuted and convicted and whey they are, the process is extremely traumatic for an adult, let alone a terrified child. When men are convicted, they often receive slap-on-the-wrist sentences, such as Brock Turner, a college student who received a 6 month sentence for 3 separate charges stemming from a violent sexual assault, but only served 3 months jail time – this as his father complained about the length of the sentence by saying that it was a “steep price to pay for 20 minutes of fun.” Seriously?

And that’s today, not half a century or more ago when sexuality was much more of a taboo subject. I distinctly remember being told that “nice women” only had sex to reproduce and that if you had sex before marriage, you were “tarnished goods” and no one would ever want you. Nice boys only married virgins. “Why buy the cow when you can get the milk for free?” Any of this sound familiar?

Elizabeth Smart – “Better to be Dead”

Elizabeth Smart, kidnapped in 2002 at age 14, held and repeatedly raped for 9 months, said that she didn’t attempt an escape for multiple reasons. First, survival mode kicked in, but on a John Hopkins University panel on May 6, 2016, Elizabeth said that one of the factors deterring her from escaping was that she felt so utterly worthless after being raped. She told the panel members:

“I remember in school one time, I had a teacher who was talking about abstinence and she said, ‘Imagine you’re a stick of gum. When you engage in sex, that’s like getting chewed, and if you do that lots of times, you’re going to become an old piece of gum and who is going to want you after that?”

As a result, Elizabeth considered suicide after rape, because, “I felt it would be better to be dead than to continue living being a rape victim.”

On CBS News in 2018, Elizabeth said, “For years after I was rescued, I didn’t want anyone to know what had happened. … Truthfully, I think I was ashamed and I was embarrassed. I didn’t want people to know that I’d been raped.”

And this was in the 2000s, not a generation ago, or two, or three or more.

For rape victims, there’s no undoing what happened. Just press forward and make the best of things. The only decision left is whether or not to subject yourself to either private or public scrutiny, possible rejection, disbelief and ridicule. If it’s bad today, it was worse when your mother or grandmother was of reproductive age. Women didn’t even have the right to vote a century ago, and very few if any women were able to support themselves without a man – either their father or husband. They needed to protect their relationships with men and their families, regardless of the personal cost. Many still do today.

When I asked a (now-deceased) women who endured repeated rapes by a close male relative in the 1940s and 50s why she never spoke out, she said, “What choice did I have? I had 5 children that needed to eat. My husband would have divorced me and I had no skills to get a job. He (the rapist) knew that and laughed about it. He delighted in the fact that I could do nothing and tortured me with it until he finally died.” I hope she danced on his grave.

If one of those children turned out to be the child of the rapist, the woman would never have known then because she was having sex with her husband as well. If discovered genetically today, it would look like she cheated on her husband – but she didn’t.

If you think this can’t possibly be your family, think again.

Sexual Assault is More Common Than You Might Think

Consider the following statistics:

  • RAINN, a nonprofit organization focused on helping victims of rape, abuse and incest states that 90% of rape victim are female. For purposes of genealogy, of course, males who are raped don’t become pregnant with the rapist’s child.
  • RAINN’s statistics don’t include children under 12, but they report that in 1993, 4.3 assaults per 1000 people occurred. If you extrapolate this to the 1990 census where the US population was 248,709,873, that means that 1,069,452 rapes occurred in the US that year, and of those, just under 1 million rapes occurred to women. According to the census bureau, in 1990, the US had 127,470,455 females of all ages. Looking at the distribution, it appears that if you subtracted both females under 15 and over 55, about half of the female population would have been between 15 and 55, or the prime rape ages. Assuming then that about 60 million women were the primary rape targets, and of those, 1.5 million or one 3% are raped every year, that means every women 15-55 has a 3% chance of being raped each year, assuming there are no women raped more than once. If you’re at risk from age 15 to 55, or roughly 40 years, at 3% chance per year, it’s no wonder that the rape statistics are so high. However, if rapes of females under 15 were included, the numbers would be much higher.
  • RAINN also reports that of 1000 rapes, 994 perpetrators will walk free, so rapists remain free to rape again – and do.
  • RAINN says that sexual violence has fallen by half in the last 20 years, meaning that before 1998, women were even more likely to be assaulted.
  • The National Sexual Violence Resource Center (NDVRC) says that one in five women will be raped at some point in their lives. Look around at 4 of your female friends or co-workers. If it’s not you, it’s one of them – and that’s just the women who report the rapes. Most don’t.
  • 80% of women know the rapist. That means that reporting the incident is going to cause drama within their family or social circle.
  • It’s even worse for children. Yes, I said worse. One in four girls will be sexually assaulted before they are 18 years of age.
  • According to the NSVRC, 63% of sexual assaults are not reported to police. According to FiveThirtyEight, 77% are not reported to police. A 1992 report titled Rape in America, A Report to the Nation reported that 84% of rapes are not reported. Personally, from discussions recently among women friends, I’d say it’s well into the 90% range, which means the estimates of how many women are actually raped, extrapolated from the reported statistics, are significantly low.
  • This paper from February 2018 on the National Study of Sexual Harassment and Assault states that 51% of women report being sexually touched in an unwelcome way. 81% of women report some form of sexual harassment or assault in their lifetime.
  • The Center for Disease Control (CDC) reports that 18.3% of US woman have been raped and 19% of college women have experienced sexual assault or rape. In Native American tribes the incidence is much higher. In 2012, the New York Times reported that in a report by the Alaskan Federation of Natives, the rate of sexual violence in rural villages is as much as 12 times the national rate. Women in Alaska and among other tribes suggest that few, if any, female relatives or friends have escaped sexual violence.
  • The Justice Department reports in 2016 that 1 in 5 college women report sexual assault, with half being rape. 21% of female graduates have been sexually assaulted while in college. Of course, this doesn’t speak to anytime before or after college.
  • The National Intimate Partner and Sexual Assault Survey from the CDC surveys in 2010 and 2011 states that about 19% of women have been a victim of attempted or completed rape in their lifetimes.
  • The Department of Justice says that from 2006 to 2010, the percentage of unreported rape was 65%.
  • This article provides statistics about on-campus rapes and this article about rape frequency in general.

If you’re feeling a bit uneasy now, and you’re thinking of your own mother and grandmother and sister and aunt – and you’ve just realized that of those 4 women, chances are that at least one of them has been raped, and possibly more, you’re probably right. Just because they never told you, or anyone, doesn’t mean that it didn’t happen. In fact, if it did happen, it’s unlikely you ever heard about it, because they probably told NO ONE. Not then and they won’t now.

No one wants to think about that possibility. But if you wonder why a child was placed for adoption, why a child was raised by grandparents, or why a Y DNA test doesn’t match the paternal surname line, especially if the mother seemed so normal and there was no hint of a domestic or relationship issue – sexual assault in one form or another may well be the answer.

Sometimes a rape is the reason behind an adoption, and rekindling that trauma may be why some biological mothers don’t welcome contact with children. Those that do may not be willing to divulge the identity, if known, of the rapist for fear of being victimized yet again by the adult child being anxious to connect with the rapist. The rapist of course would deny the rape, so the mother once again has to risk disbelief and relive the trauma and issues she thought she put behind her decades ago. Who wants to know anything about a man that violated you decades ago – and very likely got away with it. Mothers who are not forthcoming aren’t always simply being obstinate – they may have very legitimate reasons.

Adoption wasn’t always the solution women sought. Many women raised those children inside of marriages, never revealing (at least not to the child) that they were not the biological child of their husband.

Today, with more and more people taking autosomal DNA tests, a biologically unrelated father or grandfather becomes painfully obvious pretty quickly to a genealogist.

While it’s extremely unpleasant to think what might have happened to your mother or your gray-haired loving grandmother when she was younger, it’s also wrong, dead wrong, to presume that she willfully cheated. Chances are at least equal that she had no or little choice in the matter. Many, many women who weren’t actually forcibly raped were heavily coerced or drugged.

What Do We Say?

So full siblings aren’t full siblings after all or the expected father isn’t the father.

Now that the secret has been revealed, at least to you, what do you say, and to whom?

There is no single answer, and no easy one either.

In part, what you say to whom depends of the level of investment of the person or people who tested. If they aren’t interested in the results, in essence, having tested “for you,” you may decide that in the interest of causing no pain and doing no damage, not to reveal the discrepancy.

Often people who ask someone to test will inform the tester in advance that the results can hold surprises – although no one ever expects they will be the one. Asking in advance if they want to know if “surprises” are discovered may also help direct your actions.

I never disclosed the information when I discovered that my half-brother was not my biological brother when he was terminally ill. Revealing that information would only have caused him pain, and there was absolutely no reason to do that.

I invested in genealogy, including genetic genealogy for fun, not to hurt anyone. My own personal guiding creed is “do no harm.”

Every situation is different and you will simply have to let the individual circumstances and your heart be your guide.

Having said that, how do YOU process this information which has the potential to be disturbing on several levels – not the least of which is that as a genealogist, you may have invested years in researching the wrong tree.

Unfortunately, there’s no easy answer for that either. Some people reach out for counseling to help them over the rough patch.

The Benefit of the Doubt

I would suggest taking the high road and giving the female in question the benefit of the doubt unless you have actual evidence to suggest otherwise.

Please don’t pass judgement on her morality or character from the distance of decades when you can’t understand the circumstances, don’t have all of the information and she can’t defend herself.

If I have to make an error in judgement, let it be on the side of assuming the best, not the worst. Choices were few and none of them good for rape survivors. Our mothers, grandmothers and female ancestors did the best they could in the time when they lived and with the resources available to them at that time.

What she did or did not do then bears no reflection whatsoever on her love for her children, or you.

What your ancestors did or didn’t do also bears no reflection on you, today. Their actions and choices are not a curse that travels through generations.

If you loved them before, they haven’t changed. Continue to love them, with perhaps renewed or increased appreciation for their pain and the trials they faced in their lifetime.

What you discovered changed, not them. Be sure to place that discovery into historical and societal context and practice genealogical benevolence and kindness. What appear to be “lies” today may have been protection for the vulnerable then. Never assume and certainly not the worst.

Remember, you would not be here or would not be who you are if history had taken a different turn. And you’re awesome!

You, my friend, ARE the rest of their story.

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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Disclosure

I receive a small contribution when you click on the link to one of the 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.