Archiver > GENEALOGY-DNA > 2010-02 > 1266623491

From: Wayne Kauffman <>
Subject: Re: [DNA] FTDNA will introduce Family Finder (cM limit)
Date: Fri, 19 Feb 2010 15:51:31 -0800 (PST)
References: <>
In-Reply-To: <>

The 23andMe Amish/Mennonite project has picked up a reasonably large number of individuals who have pre-1850 ancestors from these communities. The individuals are exhibiting single IBD segments in the 5.0-5.5 cM range. These relevant genealogical matches reach into the mid-1700's.

I have not specifically looked at pulling out segments in the 4-0-5.0cM range. Looking at a number of individuals it appears we should be able to show some of the 'high quality' segments as being genealogically relevant. Some of these shorter segments are actually fragments of larger IBD segments identified in a previous generation or via another algorithm such as Family Inheritance. Providing a customer report with these shorter segments can make it easier to follow the break-up of a larger segment across several generations. I would be interested in seeing if FTDNA's Family Finder's 10cM limit effectively cuts off most of these 18th century matches that we see. These older single segment matches are the key to assigning a segment to an ancestor and manually separating out segment ownership in more closely related individuals.

Within the color coding scheme that Bonnie Schrack developed, and I use in the project segment reports, a quality segment is one without any blue or purple cells being present. When looking at segments <5.5cM the color coding provides guidance on what could be genealogically relevant. I think evidence to support this observation will come whenever the project segment data is pushed through PLINK and GERMLINE. After that type of processing we will have a better understanding of which segments were used to establish a relationship between 2 individuals.

- Wayne Kauffman

From: "" <>
Sent: Fri, February 19, 2010 1:26:20 PM
Subject: Re: [DNA] FTDNA will introduce Family Finder

Thanks for the update, Terry. The SNP overlap makes more sense to me than
the original claim of testing every 23andMe SNP plus more, even setting aside
the mtDNA and Y custome SNPs from 23andMe.

The 10cM threshold (vs 7.5cM for at least one segment at 23andMe) will
aggravate those who've been begging for lower and lower thresholds, thinking
they're missing out on important connections. Wayne, I know you've been
looking at lower thresholds -- have you developed a sense of how informative they
are for your Anabaptist project?


In a message dated 2/19/2010 8:46:46 AM Pacific Standard Time,

> I've updated my blog after getting some input directly from FTDNA:

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