Whoa!! Incorrect assumption. The two X Chromosomes that are received by the daughter only come from her mother, not from the father. The Father of passes on a Y Chromosome to his son, and the mother passes on an X Chromosome to her son. JFBailey www.baileywick.com -----Original Message----- From: pa-old-chester-bounces@rootsweb.com [mailto:pa-old-chester-bounces@rootsweb.com] On Behalf Of E Johnson Sent: 22 October, 2006 17:50 To: PA-OLD-CHESTER@rootsweb.com Subject: [PaOldC] Why test Y? Why test yDNA only?? 1. Because a female receives one X chromosome from each parent. So testing DNA from X chromosome (of a female subject) could not reveal from which parent the DNA had been received. You'd have to test at least one of her parents, too. 2. Testing DNA from X chromosome of a male subject, of course, would show DNA material which he could only have received from his mother. He can prove who his mother was. But that's as far back as can be ascertained, because DNA from his mother could have come from the X chromosome she received from her mother, OR from the X chromosome she received from her father (see part 1). Therefore it would not be possible to tell from which of his mother's parents the grandson's xDNA had been received. So if we text xDNA, we would have to backtrack through records of xDNA results from every generation, which wouldn't get us back very far in time. Maybe at some point in the future, if a database of xDNA matched to names existed, it would be possible to prove a lineage through testing xDNA. It would still be a lot more work to do it that way, though. Hope this helps. Liz J ------------------------------- To unsubscribe from the list, please send an email to PA-OLD-CHESTER-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message

Whoa again... Note that in my first statement, I did not say anything at all about mtDNA. My comments had concerned the reasons why X DNA is not easy or efficient to use in genealogical testing, when one wants to learn about a specific lineage. I had already read the info at the "tutorial" --which is a brief one-page explanation on the familytreedna website. I went back again to see it. But the info on that page might be a little confusing. This statement is right: > The Father of passes on a Y Chromosome to his son, and the mother passes on > an X Chromosome to her son. But this statement here is incorrect: > The two X Chromosomes that are received by the daughter only come from her > mother, not from the father. No, Not logical... Not. For now, try this very brief explanation: People receive one X chromosome from their mothers, and one X or Y chromosome from their fathers --that is, they receive one from each parent. X and Y DNA are contained inside the nuclei of cells. We test YDNA to establish who the father(s) were. We could test X DNA to find something about a person's parent, but if we test X DNA of a female, we would not know if that X DNA had come from her mother or from her father. So we don't test X DNA. We do test mitochondrial DNA, which is different material altogether. This DNA material is contained outside of the nuclei of our cells --in the cells themselves, but not within the cell nucleus. This material, mtDNA, supposedly comes only from the mother --although the suggested website does not state how that can be. (can someone explain that one??) Again: mtDNA is not the same as the DNA from an X chromosome. Mitochondrial DNA is used in genealogical research, but in a very different way: We test mtDNA in order to help determine a person's ethnic heritage. But this test does not not necessarily determine who the person's parents had been. It is a much more general test. If further clarification is wanted, I recommend that people read further, and preferably that they read beyond the statements made on only one website. Thanks again, Liz J