Tim's stats were an interesting approach (and I need to think about them more), but I don't want you to think that a negative finding is necessarily significant. There is only a 50% chance that a given segment in the parent will show up in the child, so Tim is looking at how often his percentages deviate from that number. On the flip side, a match in the child should also be found in one of the parents. If not, it may be IBS. However, I just recently learned something that might affect this with FTDNA's algorithm. At 23andMe, I've found that about 5% of my son's matches don't show up for my husband and me. For father/mother/child trios at FTDNA, the percentage seems to run higher, 10-20%. FTDNA seems to be incorporating some additional parameters beyond the length of the longest segment. In one case, a man had a match in FF with segments of 2.1,1.2, 2.0, 1.1 and *23.2 *cM (GEDmatch with 1 cM threshold). The man's mother was not declared a match in FF, but GEDmatch showed there were matching segments of 1.7and *23.2 *cM. That seems odd to me, and might account for some of the cases where a match in the child is not found in either parent. Ann On Sat, Jan 7, 2012 at 7:41 AM, Larry Vick <[email protected]> wrote: > Ann, > > Thanks for the correction. I have tried to learn from your postings and > those of others like Tim JANZEN, but I still have more to learn. I am > still thinking about Tim's revelation (at least for me) that there is more > significance to have a child share a match with me than I had previously > thought. > > If only I had appreciated my high school biology class then the way I > would today I might have done better than the "D" I got. I only got a "D" > because I was allowed to do extra credit. > > Regards, > > Larry >

Dear Ann, Can you give us some data about the lengths of the matching segments that you referred to for the 5% of your son's matches at 23andMe who don't match your husband or you and the 10-20% of your son's matches in FTDNA's Family Finder who don't match your husband or you? Sincerely, Tim Janzen -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Ann Turner Sent: Saturday, January 07, 2012 8:26 AM To: Larry Vick; [email protected] Subject: Re: [AUTOSOMAL-DNA] Subject: How do you work a 5 way FF match with few clues ? On the flip side, a match in the child should also be found in one of the parents. If not, it may be IBS. However, I just recently learned something that might affect this with FTDNA's algorithm. At 23andMe, I've found that about 5% of my son's matches don't show up for my husband and me. For father/mother/child trios at FTDNA, the percentage seems to run higher, 10-20%. FTDNA seems to be incorporating some additional parameters beyond the length of the longest segment. Ann