Its smaller than that if count just the 21K coding proteins, two copies from both parents. If perfectly mixed you start losing ancestor contributions as soon as

Its smaller than that if count just the 21K coding proteins, two copies from both parents. If perfectly mixed you start losing ancestor contributions as soon as 16 generations or 400 years. But meiosis- the halving of DNA during creation of eggs and sperm- is not perfectly random, but chunky. So ancestor dropout occurs sooner.(It is hypothesized much of the other 98% of the genome has some sort of genetic influence too.)