Re: Incest???
I was reading a book long, long time ago and also in Kisas ul Ambia. It says that Hzt Adam always had twins. They had 120 pairs a total of 240 children in all. 120 men and 120 women. The rule Allah ordained at that time was that Abil who was the first son could not marrry his sister and Kabil could not marry his sister (sister- meaning born with them) . So the rule Allah ordained was that ABIL would marry Kabil's sister and Kabil would marry Abil's sister. BUT KABIL wanted to marry his sister. So he Kills ABil but thats another story... but to make it short, during that time a pair born together could not marry each other ...
Hope it helps to some extent.