I have just sent my DNA in to Ancerstry.com. I am investigating my parental linage via the Y chromosome and my maternal linage via the mitochondrial DNA. For those that do not know, the Y chromosome is past from father to son. For instance, my father, I, my sons and their sons all have the same Y chromosome. And that fellow should be identical to that of my grandfather, his father etc. But from time to time there are small mutation that creep in. This is why all of us men do not have the same Y. And using that information one can determine how closely you one man is related to another man. The only problem is it really is telling you how close your Y chromosome is and since ever generation gets half of its genes from each parent, you have to the portion that this represents has to be divided by two for each generation. For instance only an 8th of my came from my great grandfather (my father’s father’s father). The same thing is true on the maternal line. The Mitochondrial DNA is not really our human DNA at all. It is from bacteria that got trapped inside the egg way back when and gets passed from mother to children. Men cannot pass it along so our Mitochondrial DNA comes down the linage of our mothers. Ancestry is building up a data base of DNA to help its members not only get insight into their genetic past (in the limited way I described) but also to connect to other members that are participating in the data base (provided they give permission). So in my cased, I know all the sons of my great grandfather (paternal linage). But if my great grandfather, Abraham Goldfinger (I was a Goldfinger when I was born), had a brother, who had a son, who had a son, who had a son that was also in the data base, I could discover him. I think we would be fourth cousins. Same thing on my mother linage side. In this case I would have to go back even further since to the sisters of my great grandmother, Bessie Levy (Borodinsky). She had sisters for instance that stayed in the Ukraine and I am not sure what happened to all of them (although it is likely that they were killed in the Holocaust like all the other members of my family that stayed behind that I know of). Of course there can be man relatives with the same y-chromosome that goes back even further than Abraham Goldfinger. And I can also use the same technique to find other relatives if I can get some of my cousins to cooperate. For instance there is a copy of my mother, father’s y chromosome living in Israel (we are third cousins). The is a copy of my mother’s mother’s father’s Y chromosome in a second cousins body. In fact, I might be able to get y and mitochondrial DNA from all my great grandparents (but it is going to be a lot of work and a lot of money). Not sure I want to go this far especially since, I know so much about my families genealogy and they are pretty uniformed. In 1880, they all lived in eastern Europe (Galicia for the most part). They were all Jewish. The all spoke the same language, Yiddish, and the all had the same religion. They pretty much at the same kind of food. And they were all in the clothing business (tailors and tanners).
I am going to have my genes screened by a company, Navigenics that was formed by my dear friend David Agus (a great scientist), The idea is to determine if one has high probability for some disease (like heart disease) where there is some preventative action that one can take. Your info goes into a data base where it is compared to indicators of potential problems. You pay a onetime fee and then a yearly fee if you want to keep getting updates. I am a bit on the fence about this since it may just give me more to worry about but I also believe that this is the future of medicine. The December issue of Wired has a good article about all this.