I'm not endorsing cousin fucking. I just think "cousin fucker" is the funniest insult I've heard in a while. What should the cut off be? 2nd cousins? Technically Kevin Bacon is a cousin fucker. Him and Kyra Sedgwick are ninth cousins once removed. Should they all just be labeled "cousin fuckers"? Don't marry a cousin unless you want tarded kids folks.
If you look far enough into everyone's family trees aren't technically most of us cousin fuckers? 2nd grade seems a reasonable cut-off to me. Unless maybe it's a big royal family that has a tradition of 3th grade cousin fucking.