If they wish to and it's safe I find no problem with incest.
But OP mentioning it in the same breath as a marriage? Sex is in the sex topic, marriage is marriage topic. Sex does not equal marriage.
Only sex that should be illegal should be exessively violent sex such as guro. So once you draw blood, then you've crossed the line.(Unless said blood came from a virginity being taken.)
Only two kinds of sex I myself can't stand is Guro and Scat. First one due to the loss of life, second due to chance of massive infection. Everything else I can understand even if I myself don't partake in the majority of them.
Wisdom overcomes all ignorance if people learn it. Educate yourself, TYT and RT america on youtube.
