Recently, GedMatch introduced a tool, Lazarus, to figuratively raise the dead by combining the DNA of descendants, siblings and other relatives of long-dead ancestors to recreate their genome.  Kind of like piecing Humpty Dumpty back together again.

Blaine Bettinger wrote about using Lazarus here and here where he recreated the genome of his grandmother.  I’d like to use Lazarus to see how it works with one pair of siblings and a first cousin.  Blaine was fortunate to have 4 siblings.  I have a much smaller group of people to work with, so let’s see what we can do and how successful we are, or aren’t.  But first, lets talk about the basics and how we can reconstruct an ancestor.

The Basics

An individual has 6766.2 cM of DNA.  Both parents give half of their DNA to each child, but not exactly the same parental DNA is contributed to each child.  A random process selects which half of the parents’ DNA is given to each child.  Different children will have some of the same DNA from their parents, and some different DNA from each parent.

Obviously, the DNA contributed to each child from a parent is a combination of the DNA given to the parent by the grandparents.  Approximately half of the grandparent’s DNA is given to each child.  In many cases, the DNA contributed to the child from the grandparents is not actually divided evenly, and we receive all or nothing of individual segments, not half.  Half is an average that works pretty well most of the time.  It’s a statistic, and we all know about statistics…right???

Therefore, children carry 3383cM of each parent’s DNA.  Each sibling carries half of the same DNA from their parents.  From the ISOGG autosomal DNA statistics chart, each sibling actually carries 25% of exactly the same DNA from both parents, 50% where they inherited half of the same DNA from one parent and different DNA from the other parent, and 25% where the siblings don’t share any of the identical DNA from their parents. This averages 50%.

This chart, also from ISOGG, sums up what percentage of the same DNA different relatives can expect to carry.

Recreating Ferverda Brothers

I have a situation where I have a person, Barbara, and two of her first cousins, Cheryl and Don, who are siblings.  This is the same family we discussed in the Just One Cousin article.

In this case, Cheryl and Don share 50% of Roscoe’s DNA.

Barbara shares 12.5% of Hiram and Evaline’s DNA with Cheryl and 12.5% with Don, but not the same 12.5%.  Since siblings share 50% of their DNA, Barbara should share about 12.5% of Cheryl’s DNA and an additional 6.25% that the Cheryl didn’t receive from Roscoe, but that Don did.

Translating that into cMs, Barbara should share about 850 cM with Cheryl and an additional 425 cM with Don, for an approximate total of 1275 cM.

At http://www.gedmatch.com, I selected the Tier 1 (subscription or donation) option of Lazarus and was presented with this menu.

My first attempt was to recreate Barbara’s father, John W. Ferverda.  I allowed 100 SNPs and 4cM because I was hoping to be able to accumulate more than the required 1500cM of matching DNA for the kit to be utilized as a “real kit,” available for one-to-many matching.

I then experimented with the various SNP levels, leaving the cM at 4.

The resulting number of cM of just over 1300, no matter how you slice and dice it, is very near the expected approximation of 1275.

Using the Lazarus tool, I created “John Ferverda” by listing Barbara as his descendant and both Cheryl and Don as cousins.

To create “Roscoe Ferverda,” I reversed the positions of the individuals, listing Don and Cheryl as descendants and Barbara as the cousin.

These two created individuals, “John” and “Roscoe” should be exactly the same, and, thankfully, they were.

Both recreated “John” and “Roscoe” represent a common set of DNA from the parents of both of these men, Hiram Ferverda and Evaline Miller based on the matching DNA of their descendants, Barbara, Cheryl and Don.

The way Lazarus works is that all kits in Group 1, the descendants, are compared with Group 2, other relatives but not descendants.  The descendants will carry some of Roscoe’s DNA, but also the DNA of Roscoe’s wife, the mother of Don and Cheryl.  By comparing against known relatives but not direct descendants, Lazarus effectively narrows the DNA to that contributed only by the common ancestor of group 1 and group 2.  In this case, that common ancestor would be John and Roscoe’s parents, Hiram Ferverda and Evaline Miller.  By comparing the descendant and non-descendant-but-otherwise-related groups, you effectively subtract out the mother’s DNA from the descendants – in this case meaning the DNA of John Ferverda’s wife and Roscoe Ferverda’s wife.

In other words, the descendants, above, are NOT compared to each other, but instead, to each one of the not-descendant-but-otherwise-related group.

Unfortunately, none of the kits generated was over the 1500 cM threshold.  I remembered that there is also a second cousin, Rex, whose DNA we can add because he descends from the parents of Evaline Miller.

Adding Rex to the mix brought the resulting “Roscoe” kit to 1589.7 cM and the resulting “John” kit to 1555.7 cM, both now barely over the 1500 threshold – but over just the same and that’s all that matters.  Soon, we’ll be able to utilize both of these kits for direct matching as a “person” at GedMatch.  Now how cool is that???

You receive four pieces of output information when you create a Lazarus kit.

First, a comparison between the descendants (Group 1 above, Kit 2 below) and each of the cousins and related-but-not-descendants individuals (Group 2 above, Kit 1 below), by chromosome.

John W. Ferverda

Processed: 2015/01/09 17:32:41
Name: John W. Ferverda
SNP threshold = 100 cM
Threshold = 4.0 cM
Batch processing will be performed if resulting kit achieves required threshold of 1500 cM.

Contributions:

Obviously, these are only snippets of the output for chromosome 1.  You receive a chart of this same information for all of the chromosomes of the people being compared.

Second, a chart that shows the resulting matching segments.

Resulting Segments:

At the bottom of this second set of numbers is the all-important total cM.  This is the only place you will find this number

Third, a list of the original kits that have match results between the two groups.

Original Kits match with result:

And finally, a summary.

196074 single allele SNPs were derived for the resulting kit.
37068 bi-allelic SNPs were derived for the resulting kit.
233142 total SNPs were derived for the resulting kit.
Kit number of Result: LX056148
Kit Name: John Ferverda 8
Your Lazarus file has been generated.

Is this as good as the real McCoy, meaning swabbing John and Roscoe?  Of course not, but John and Roscoe aren’t available for swabbing.  In fact, John and Roscoe are both probably finding this pretty amusing from someplace on the other side, watching their children “recreate” them!

I can hear them now, shaking their heads, “Well I never….”

They should have known if they left Cheryl and me here, together, unsupervised that we would do something like this!!!

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