Comments on: How Many Ancestors Share Our DNA?

By: Using Genome-Wide SNP Scans to Explore Your Genetic Heritage

Using Genome-Wide SNP Scans to Explore Your Genetic Heritage — Wed, 04 Aug 2010 18:55:45 +0000

[...] Jostins at Genetic Inference kindly looked into my questions and offered some helpful and creative insight. Using a statistical [...]

By: Pamela Rowe

Pamela Rowe — Sun, 10 Jan 2010 20:15:16 +0000

I am a female and more closely related to my paternal line, 53.13%, according to Relative Finder. Almost everyone of my matches comes from my father’s side.
Some of his relatives, I am even more related to because of the recombination. On the average, it looks as though I may lose a few cm’s with most; although, many of our matches have remained exactly the same.
One particular high/distant cousin match for him, totally disappears for me.
All very interesting!

By: Leigh

Leigh — Tue, 24 Nov 2009 22:16:52 +0000

Was pleased to read about girls being closer to the maternal line. . .

By: E

Mon, 16 Nov 2009 16:10:03 +0000

“….you are, on average, slightly more closely related to your maternal line (your maternal grandmother, your mother’s maternal grandmother, etc) than you are to you paternal line (your father’s paternal grandfather, etc).”

Cool.

But, aren’t most people going to be more like their fathers, then, than their mothers since they should inherit more directly *groups* or *packages* of genes that did not recombine (i.e. that remain linked)?

By: Richard T

Richard T — Sun, 15 Nov 2009 06:36:45 +0000

Doh, can you tell it has been a while since my last genetics class? I guess the answer to my question above (which describes the situation of many 23andMe /DecodeMe customers) basically comes directly from the definition of a centimorgan. Feel free to delete the question.

By: Richard T

Richard T — Fri, 13 Nov 2009 19:59:47 +0000

Great, thanks! Your first chart above addresses one side of the issue: Given recombination, what is the probability you will inherit NO DNA from a given ancestor x generations back?
The other side: Given recombination, and given that you KNOW you inherited y cM of autosomal DNA from a particular line of ancestors, what is the probability you will inherit AT LEAST y cM of DNA from an ancestor x generations back? This plot should look quite different, and I guess it should depend on the length of the chromosome involved, right?

If so, can you at least give a simplified answer, assuming an average autosome length?

By: wayne

wayne — Fri, 13 Nov 2009 11:05:59 +0000

How do the simulations change when there are 2, 3, 4…. common ancestors present within specific generations? What you provide is the theoretical minimum.