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    1. Re: [AUTOSOMAL-DNA] Question about X-DNA and sisters
    2. Ann C Gilchrest
    3. Hi Greg, Just based on the fact that C & B share no DNA tells you that A & B have different fathers. There are no cases where first cousins don't share DNA. Ann Gilchrest -----Original Message----- From: AUTOSOMAL-DNA [mailto:[email protected]] On Behalf Of Greg Lovelace Sent: 23 January, 2018 11:41 To: [email protected] Subject: [AUTOSOMAL-DNA] Question about X-DNA and sisters Greetings, all. I am working on a project that I need a little help on. I've tried going through all the DNA blogs and still can't come up with a definitive answer, so I'm hoping some of you have faced this situation and can give some guidance. I am looking at two sisters and their female 1st cousin. The sisters (call them "A" [Shirley] and "B" [Boni]) were raised as full siblings. However, they only share ~1700 cM of DNA at the 5cM threshold, indicating to me that they are only half-siblings. Is this a correct assumption? Now the cousin (call her "C" [Doreen]) and "A" share ~860 cM of DNA, placing them correctly as full first cousins (the average for 1st cousins is 874 cM). The father of "A" and "B" is the brother of the mother of "C." At the 5 cM threshold, "B" and "C" have no shared segments of DNA. And "A" and "B" only share about 50% of the DNA on their X-chromosome, indicating to me that they only share one parent. Is that a valid assumption? Thanks for any insights. Peace, Greg Lovelace Part of the Tree Research Services 683 Edmonds Drive Charleston, SC 29412 <mailto:[email protected]> [email protected] <> ______________________________ For answers to Frequently Asked Questions about mailing lists, please see: ------------------------------- 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

    01/23/2018 05:06:09