I'm not Linda. I don't even play her on TV <g> but this is precisely where autosomal DNA can accomplish what Y-DNA and mtDNA cannot do. Y can only tell that two males are related and have a probable common ancestor (or don't) and mtDNA can tell relationship through the straight maternal lines (mother's mother's mother on back) but autosomal testing can tell you probable "cousinships" between two individuals no matter which sides of the family is the one where the relationship occurred. While the "proof" won't be conclusive in the case you present below--it could help you rule out or reinforce your hunch if 23andme finds a probable cousinship between you and the descendant of your possible ancestor--assuming, of course, that the two of you are both tested and that you have no other possible relationship on other areas of your pedigrees. Joan In a message dated 6/1/2010 8:18:24 A.M. Eastern Daylight Time, [email protected] writes: Linda, I agree with Rita. Thank you for all of your knowledge that you have shared with all of us these past few years. I have a question for you about using DNA testing to prove relationships. I have spent years trying to prove who my maternal grandfather's father was. I found a man that I suspect was his father and need to prove it. This man never married my grandfather's mother (not unusual I guess), but he later married two other women. One of whom had a son with him. This son had two daughters who are still living, as is my mother (age 96). Can I use DNA testing, such as "23andme" to prove that they are related? Thanks so much for all of your help to others. Pat Robinson