Aaah...that's the tricky bit. On 18 November 2011 20:23, Ann Turner <[email protected]> wrote: > Thanks for the offer. I would need raw data for the matching party as well, > preferably someone has also tested a father and mother. > > Ann > > On Thu, Nov 17, 2011 at 9:20 PM, Samantha John <[email protected] > >wrote: > > > Ann, > > > > I could send you my son and both his parents, or me and both mine, all > done > > at 23andMe if you wish? In both cases, especially my son's, there are > > matches with him that can't be pinned down to either parent. > > > > Regards > > Sam > > > > On 18 November 2011 06:19, CeCe Moore <[email protected]> wrote: > > > > > > > > Ann, > > > > > > I think I have a set that I can send you. I could also send you mine > and > > > my parents, but my dad is at FTDNA and my mom is at 23andMe, so I don't > > > know if that would work. > > > > > > CeCe > > > > > > > > > www.yourgeneticgenealogist.com > > > www.studiointv.com > > > > > > > > > ---------------------------------------- > > > > From: [email protected] > > > > Date: Thu, 17 Nov 2011 08:19:52 -0800 > > > > To: [email protected] > > > > Subject: Re: [AUTOSOMAL-DNA] Fundamental autosomal DNA question > > > > > > > > No, unfortunately. I need raw data with father/mother/child trios on > > both > > > > sides of the match so I can use phased data. That's not easy to come > > by. > > > > > > > > Ann > > > > > > > > On Thu, Nov 17, 2011 at 7:41 AM, CeCe Moore <[email protected]> > > > wrote: > > > > > > > > > Ann, > > > > > Thanks for sharing your experience. > > > > > Have you looked at the raw data on those long segments (over 10 cM) > > to > > > > > determine if they really are IBS? I find those lengths very > > surprising. > > > > > With your data, you noted that about 95 percent of the time what I > > said > > > > > earlier will hold true, but that other 5 percent is troubling. I > > > certainly > > > > > would like us all to be able to be confident of the validity of the > > 10 > > > cM > > > > > blocks and above, if not the 7 cM and above. > > > > > CeCe > > > > > Sent via BlackBerry by AT&T > > > > > > > > > > -----Original Message----- > > > > > From: Ann Turner <[email protected]> > > > > > Date: Thu, 17 Nov 2011 12:19:52 > > > > > To: <[email protected]> > > > > > Subject: Re: [AUTOSOMAL-DNA] Fundamental autosomal DNA question > > > > > > > > > > One way to study the problem is with father/mother/child trio data. > > If > > > the > > > > > child has a match not found in either parent, it is possible > (indeed > > > I'd > > > > > say likely) that the segment is Identical by State, not Identical > by > > > > > Descent. > > > > > > > > > > Ancestry Finder at 23andMe lets you look at segments down to 5 cM / > > 700 > > > > > SNPs. For actual numbers in one case, my son has a total of 231 > > > segments > > > > > listed with names attached. 67 of those are found only in the child > > > (29%). > > > > > The breakdown by segment size is > > > > > > > > > > 4/76 > 7 cM, longest 11.1 cM (5%) [This seems consistent with a 95% > > > > > confidence interval] > > > > > 7/37 6-7 cM (19%) > > > > > 56/119 < 6 cM (47%) > > > > > > > > > > FTDNA seems to have a cutoff of 7.7 cM / 500 SNPs (that's by > > empirical > > > > > observation -- has anyone found a shorter longest segment?). I have > > > data > > > > > for one father/mother/child trio that seems particularly dicey, > with > > > 22/100 > > > > > matches in the child not found in either parent. The segment sizes > > > ranged > > > > > from 7.7 to 12.90, with a median of 8. Other trios I've looked at > > seem > > > to > > > > > run about 15%. > > > > > > > > > > Ann Turner > > > > > > > > > > On Wed, Nov 16, 2011 at 1:02 PM, CeCe Moore <[email protected] > > > > > wrote: > > > > > > > > > > > > > > > > > When I say "legitimately" match, I mean an IBD segment that would > > > meet > > > > > the > > > > > > company's matching threshold, not a segment made up of stretches > of > > > IBD > > > > > and > > > > > > IBS pieced together. > > > > > > > > > > > > I'm not saying that it is impossible for a match over ~7 cMs to > be > > > IBS, > > > > > > but very unlikely. (I was going to write ~10 cMs in my response, > > but > > > > > > thought that might be a bit conservative.) I know that it is > > > > > theoretically > > > > > > possible, but in my thousands of hours of atDNA research, I have > > yet > > > to > > > > > see > > > > > > proof of one. Can you please show me an example of an IBS match > > over > > > 7 > > > > > cMs? > > > > > > (I know that Ann Turner has seen lots of them between 5cMs-7cMs. > > > We'll > > > > > see > > > > > > if she responds with a larger one.) > > > > > > > > > > > > If enough of a portion of the segment is IBS that it doesn't show > > up > > > in > > > > > > your parent (i.e.- make the company's threshold), then it will > > > obviously > > > > > > reduce the authentic match to a point that is not worth > pursuing. I > > > have > > > > > > chased far too many matches under 7 cMs to recommend doing the > > same. > > > > > > > > > > > > > > > > ------------------------------- > > > > > To unsubscribe from the list, please send an email to > > > > > [email protected] with the word 'unsubscribe' > > without > > > > > the quotes in the subject and the body of the message > > > > > > > > > > > > > > > ------------------------------- > > > > > To unsubscribe from the list, please send an email to > > > > > [email protected] with the word 'unsubscribe' > > without > > > > > the quotes in the subject and the body of the message > > > > > > > > > > > > > ------------------------------- > > > > To unsubscribe from the list, please send an email to > > > [email protected] with the word 'unsubscribe' without > > > the quotes in the subject and the body of the message > > > > > > > > > ------------------------------- > > > To unsubscribe from the list, please send an email to > > > [email protected] with the word 'unsubscribe' without > > > the quotes in the subject and the body of the message > > > > > > > ------------------------------- > > To unsubscribe from the list, please send an email to > > [email protected] with the word 'unsubscribe' without > > the quotes in the subject and the body of the message > > > > ------------------------------- > To unsubscribe from the list, please send an email to > [email protected] with the word 'unsubscribe' without > the quotes in the subject and the body of the message >