It's crazy how fast one becomes essentially not related to their forebearers. I mean, it makes sense from a mathematical perspective but humans are bad at perceiving big numbers and thinking about exponentials/logarithms. There's more on this wiki page. Essentially, you're great great grandparents are about as related to you as any random person, or so. Or maybe it's you're triple great grandparents... blood lines are pseudo-science, is what I'm saying.