Thanks for responding. Let me make sure I understand the x chromosome test results. Men get the y chromosome from their father and the x from their mother. Women get one x from each parent. I looked at the father and the son. The son and I don't match on the x chromosome which makes sense because I don't think we are related through his mother. The father and I do match on the x so that means we are related through his mother and either my father or mother. But I've pretty solidly eliminated my father so it must be my mother. This agrees with the hypothesis that I'm working on. The mtDNA would not tell me a whole lot more other than that the line goes straight up our respective maternal lines. Correct?
Thanks again. Isn't this stuff fascinating?