Wellll Noah had 4 sons, and it is considered that we have about 3-4 "major" races. (lol, funny image I know)
But who knows, maybe families were more diverse back then? Anyway realistically I think that if Noah took his family with him that would include his sons, their wives(possibly more than one per son), their children(who may have been old enough to have wives of their own), any servants that belonged to them, and maybe even more generations considering the life span of people during that time.
I'm pretty sure that the flood isn't the only Judaism event that is shared globally, but it's difficult to pinpoint them because Creationist scientists get little to no credit so even if they do find something it's hard to get the info out there. And we all must have some sort of common ancestor anyhow- even with differing races, we aren't different enough to come from completely different sources. We wouldn't all be human if that were the case. We would be like horses and donkeys, lions and tigers, chimps and Apes... instead, we're more like varying dog or cat breeds-which were also created from a lot of interbreeding FYI. (Healthy mutts for the win!)
What I want to know is what ethnicities that died during the flood- and if any of the "mutations" we see occurring in people today are just ancient genes from dead races that occasionally get enough dominance to become present? (Silly example most probably because I'm not scientifically minded just a silly thinker, but what if heterochromia was a defining attribute of a race that no longer exists?)