As an added note, that 2% roll of the dice is most likely for anemia. There's some other conditions that also crop up early as possible mutations from interbreeding but it takes a couple successive generations before it starts getting into anything really dangerous.nezroy said:1) The risk of genetic defect showing up in 1st cousin offspring are GREATLY exaggerated. Yes, there IS some increased risk, no question, but it's minor. In fact, the increased risk level of birth defect for first cousins is about the same as the increased risk level for a mother over the age of 40; in both cases, about 2% above baseline (3% being baseline, so 5% for first cousins/mother over 40). Note that because of the nature of genetics and powers of 2, this is one of those things that is really bad for full siblings, sort of bad for half siblings, and not really all that bad for 1st cousins, and rapidly falls off after that to insignificance after 2nd cousins. Now there IS some risk when the practice is repeated generation after generation, because of the potential to accumulate rare genetics over many generations.
With one critical caveat: some people do carry partial genetic data for some serious disorders, if their partner doesn't have the other half then everything's fine and it may or may not get passed on, but if both have a shared genetic history there is a substantially higher risk for that disorder. But I kinda doubt that's an issue here.
In random trivia: the last common female ancestor for everyone on the planet is believed to have lived 40k years ago. So we are all related, just not, you know, closely.