Re: Why so few matches? #dna


Jeffrey Mark Paull
 

In response to Cindy Gallard's question, "Why so few matches?," there
is a very simple answer as to why the results of autosomal DNA tests
will virtually always show many more genetic matches than the results
of Y-DNA tests. It boils down to a genetic numbers game. Ancestry,
23and Me, or FTDNA autosomal DNA tests will identify genetic matches
from all of your genetic lines, while the Y-DNA test focuses on a single
genetic line only -- the patrilineal line.

As an example, an autosomal DNA match at the 5th cousin level descends
from a common 4th-great-grandparent, which could be >from any one of 64
different genetic ancestral lines, irrespective of whether that line is
maternal or paternal. A 6th cousin descends >from any one of 128
different ancestral lines, and so on. In contrast, all Y-DNA genetic
matches on an individual's match list descend >from a single patrilineal
line.

Another important factor is the relative number of people in the testing
database. Because there are so many more people who test their autosomal
DNA compared to the number who test their Y-DNA, the chances of finding
genetic matches are much greater in the larger autosomal DNA databases.

The combination of both of these factors accounts for the much higher
number of genetic matches that are seen on autosomal DNA genetic match
lists. Reporting less than 100 genetic matches is not uncommon for the
results of a Y-DNA test; I have seen cases where an individual had no
Y-DNA genetic matches reported at all.

All the Best,

Jeffrey Mark Paull

---
From: Cindy g <gallardc@...>
Date: Sun, 11 Nov 2018 16:10:13 -0700

Over the years I have had 39 people people tested. Typically, the matches run into the thousands if not tens of thousand. I have one person whose test results found less than 100 matches. This was the Y chromosome test. Can anyone explain why this might be?
...

Join main@groups.jewishgen.org to automatically receive all group messages.