Shalom.

Personally, I believe every male on planet earth can be traced back to Noah, since he was the bottleneck after the Great Flood (Scripture gives me no indication that this was a figurative occurrence limited only to Mesopotamia). If the problem you suggest is indeed the reality, then theoretically all males today would have the exact y-chromosome markers as Noah. But that is certainly not the case because of mutation within the human genome since Noah. If one of Isaak’s descendents or Isaak himself (or any patriarch) had a mutation in Y-data, then his direct male descendants would have that same mutation in their Y-data , unless some of those descendants had more mutations which overlapped or overwrote previous mutations. This in fact happens all the time, in every generation, which is why yDNA and mtDNA testing is so useful in traditional genealogy research. It helps genealogists triangulate where mutations occured and it also helps reinforce a person’s genealogy paper trail which is often filled with many holes and speculations. DNA leaves little room for speculation. (=

Thanks for bringing up such an important point.

If you want to see how useful DNA testing is, click on the Family Tree DNA link in the right column and see if your Surname already has a DNA project underway. You’ll understand the ramifications once you’ve actually been tested and see your own results and compare them to relatives.