Speaking of 'incest', I was reading today's edition of the LA Times when I ran across an article about birth defects among first cousins offspring. It turns out that the risk of such defects does not increase as what was previously feared as compared to completely unrelated parents. The genome researchers who made this discovery say there is no need to continue practice of the societal taboo nor discourage marriage between first cousins. Marriage between siblings or parents/offspring is still a 'no-no'.
The world keeps changing the rules.