In other words: How close is too close for a marriage? Bear in mind that everyone is distantly related to their spouse.
Assume both people are consenting adults, obviously.
- First CousinVote A
- Second Cousin (Parents Cousin's Children)Vote B
- Third Cousin (Grandparents Cousin's Grandchildren)Vote C
- SiblingVote D
- Further then thatVote E
Most Helpful Guy
Knowing that first-cousin procreation doesn't have a terrifically higher rate of genetic problems than two completely unrelated people, I don't see why it has to be restricted at that point. I'm not even sure I would restrict it to siblings, as long as they are consenting adults and are responsible for what they do.
Some of our distaste for incest is because those people grew up close to us or are familiar-looking. But people legally marry childhood friends and familiar-looking friends all the time.
The rest of our distaste is just cultural and doesn't actually have much to do with the results of procreation, even if we use those to justify it. Hell, incest used to not even necessarily involve family members. In some places, you couldn't marry someone if your sibling had married their sibling. It's not a hard-and-fast system of morality, it's a cultural disgust, like homosexuality. If in modern times we can recognize that love is more important than legal tradition, and thus legalize gay marriage, we shouldn't be putting such a taboo on close-relative marriages.0