I have two people who have both autosomal DNA tested. I have both of their match lists which contain all the people each of them matches to.
For each person that each of them match to, I have:
- The number of segments they match on,
- The total centimorgans (cM) and SNPs that they match on, and
- The centimorgans and SNPs of their largest match.
If these two people match each other with approximately 3384 cM (at Family Tree DNA, other companies be slightly different), then we know that they are either parent-child, identical twins, or the same person who tested twice.
We can easily figure out if they are identical twins or the same person who tested twice since almost all the matches between the two will be the same. If the match lists are quite different, then we know we have a parent and child.
My question is: Given the match data for both people, is there any way we can tell who is the parent and who is the child?