well done---thank you--- -----Original Message----- From: bmacliam@aol.com Sent: Saturday, January 14, 2012 3:12 AM To: wilson@rootsweb.com Subject: [WILSON] DNA explanation Sorry if this is a repeat of other information, but here's an explanation of how DNA works. Men are XY, women are XX. Mother always supplies X to a child (but mom's 2 X's are NOT the same, so it's not a reliable tools for genealogy). Father supplies either X to a daughter or Y to a son (dad's X came from HIS mother, but which X is unknown). Since a father always passes his Y to all his sons, and they pass their Y to all their sons, etc, this is the way to trace the MALE line from father to grandfather to great-grandfather, etc. If a man has his Y tested, there is no reason for his brothers or sons to test, since they will be IDENTICAL (unless, of course, someone was adopted, or a step-relation). There is NO WAY to trace a woman to her father except through her brother's Y. Since the X is unreliable for testing, another method entirely is used for maternal lineage. All cells have 2 types of chromosomes: Nuclear DNA (the X, Y and 21 others) are in the cell nucleus and come half from mom and half from dad - these define us as unique individuals. Mitochondrial DNA (or mDNA) are found in the mitochondria (not the nucleus) which is an internal structure of cells. Mitochondria are in the mother's egg and pass unchanged to the child - the father's DNA has no part in this. Therefore, tracing anyone's mDNA leads directly to mother to grandmother to great-grandmother, etc. So you can see the difficulty of an only-child daughter trying to trace her father's line - she would need to find a male cousin on her father's side to do a Y-test. Likewise, an mDNA test will not help at all with family names, since women's names usually change with each generation. Brad Wilson BMacLiam@aol.com R1b1a2 ------------------------------- To unsubscribe from the list, please send an email to WILSON-request@rootsweb.com with the word 'unsubscribe' without the quotes in the subject and the body of the message