...It was many chapters later in genesis that it mentioned not to marry your first cousin or closer.
I think you mean Leviticus.
It was stated after the birth of a very hairy guy, can't remember the name now, but was of what would be considered incest today. Me, I like kissing some of my cousins, but that us far enough for me ;-)
Esau was the "hairy guy," I believe. Yes, incest- either that, or it didn't happen. Personally, I don't think it happened.