What to say about a match in many chromosomes

+2 votes
118 views
When I look at the list of my DNA matches in Gedmatch, most people share only one of the 22 pairs of chromosome, a few share two. I found one person sharing as many as 5 chromosomes. What does that tell me about that person? Thanks.
in Genealogy Help by Harry Angus G2G2 (2.9k points)
retagged by Lynda Crackett

2 Answers

+8 votes
 
Best answer
The number of chromosomes alone will not tell you anything much. What you need to consider is the size of the match (number of cMs) and which segments. The size of the match will help you to determine how close the relationship may be and you can use the segment information in grouping matches to help identify common ancestors.
by Lynda Crackett G2G6 Pilot (630k points)
selected by Harry Angus
Thanks a lot.
Harry, Thanks for the best answer star.
+2 votes

As Lynda mentions, the number of chromosome pairs on which matches occur isn't particularly significant in determining a relationship. There are two "lengths" which are used for matching on gedmatch:

- a single sequence of length 7 cM or more on a single chromosome pair that is identical for two persons is a "match"
- the sum of the lengths of all such matches is the total length.

The total length of all matches provides an indication of the relationship (2nd cousin, great-grandparent, etc). So the number of chromosome pairs on which matches occur isn't used to indicate a relationship. However, a larger number of matches contributes to the total length, which is an indication.

Matches across several pairs of chromosomes is very useful, however, when you start mapping chromosomes to determine on which chromosome (X or Y) of the pair the match occurs. So, more is better for that reason.

by Bruce Veazie G2G6 Mach 5 (57.6k points)
edited by Bruce Veazie

Related questions

+4 votes
1 answer
+9 votes
3 answers
+13 votes
2 answers
+4 votes
1 answer
250 views asked Dec 24, 2019 in Genealogy Help by Lance Martin G2G6 Pilot (101k points)
+2 votes
1 answer
+7 votes
2 answers
+2 votes
2 answers
121 views asked Dec 30, 2016 in WikiTree Tech by anonymous G2G Rookie (190 points)
+11 votes
1 answer
161 views asked Aug 11, 2016 in The Tree House by Dave Dardinger G2G6 Pilot (408k points)

WikiTree  ~  About  ~  Help Help  ~  Search Person Search  ~  Surname:

disclaimer - terms - copyright

...