I have a feeling the DNA testing will show alot of adoptions over the years.
DNA testing has shown that about 10% of us are not born to the man who mom said was dad. This found when geneticists track down family trees. About 30% of people who actually go out to test their paternity find they are not the father.
But as far as genetics go, human beings were a very mobile lot, and when mobile, liked to interbreed with the local population as much as possible. We are all very closely related.
And cuckolding...