I realize the passing of genes is approximately 50/50 (reference Generational Loss of Data with DNA testing) with each generation and which genes are passed are commonly referred to as 'random' based on existing science.

I read the tutorial and then watched the FamilyTreeDNA hour plus long tutorial video on using the Chromosome Browser as well as some videos on their YouTube channel.

Like pointed out in one of the videos.. the 50/50 does not always apply and certain chromosomes can be preserved across generations.

Looking at my known relatives to a common shared ancestor I noticed this in Chromosome 1.

The main display person (dark blue background) and GREEN are half-siblings and share a common ancestor pair who is there great-grandX.

  • Purple is the grand son of dark blue.
  • Blue is GGGG-granddaughter of the common pair from a completely different child of the common pair.
  • Orange is a GGG-granddaughter of another child of a common ancestor pair.
  • Yellow is one of about 4 others of 350 matches who have a small sliver in the that same segment of that area.

enter image description here

This segment starts at 202478548 and in the matches so far go for at least 19.29 cMs to 217120123 (the orange).

Is there such a thing as a common family pair segment region (i.e. the 202.. to 217..) that could be considered something like a "trait" (terminology may not be correct) that can be used to hone in on a specific set of relatives (or one of their ancestors) and should it be specifically looked for or utilized as a tool even at smaller segment sizes?

In other words, I realize I should look for other alignments / strong matches / longer segments as well but is it a proven and reasonable technique to hone in on a specific segment range of a single Chromosome to identify a particular relative?

Partial Chromosome browser screenshot Note: I am only showing part of the overall chromosome browser as I found the part of Chromosome one unique for such distance matches.

  • I've read through this several times but I'm not really clear what you're asking. Your terminology is slightly confusing - you don't find 'traits' in DNA (you find genes that encode for traits). Is your question basically whether the fact that all 5 people share the same small segment in chromosome 1 suggests they all share a common ancestor?
    – Harry V.
    Commented Aug 25, 2015 at 13:34
  • @vervet Kind of, I KNOW they share a common ancestor set (Father/Mother) which were born 200 years ago but descend from different children of that set. I am asking is it reasonable to try to use that common shared segment to locate other matches of that pair of common ancestors or possibly even further back?
    – CRSouser
    Commented Aug 25, 2015 at 13:47


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