Mapping your Autosomal DNA?

[DavdJ]

I thought something was off, just wanted to make sure. Thanks for the confirmation.

[keigh]

Looking at the idea proposed has been interesting, but how would one go about figuring out the percentages of DNA possible in a family or families that are highly inter-married?

[DavdJ]

I've wondered that myself. Back in the late 1700's I had a family that did that and when I start to find their DNA it's scattered like a big puzzle.

[S9 H9]

There are a couple of problems you have to overcome.

First, the "total" of shared chromosome given in FF, given in cM, includes adding up half-identical regions starting at a very low threshold. These small regions, what some people call "segments", can be artifices, that is, only IBS and in FF their existence could be a false positive (that is, based on the superposition of small HIRs that are overlapping.)

Secondly, and this is particularly problematic as you go searching for your older ancestors, that little bit of chromosome you want to assign to family F may also be existent in family G, and indeed in many people contemporaneous with your ancestor of interest. For example, many of your 8th great grandparents could have already been related to each other, even if distantly.