Close but no fucking cigar. but close.

I've been hot for my cousin since we were teens. She knows it. I know it. We're both in our middle thirties. Both are recently divorced. Kids. So last weekend I give her a ride home from a party at the house of a mutual good friend. She's fucked up on booze and weed. A rarity for her. I'm driving so all I got is a mild buzz on. We get to in front of her house, her usual peck on the cheek thank-you turns into a full out tongue in mouth make out session. My cock turns into a fucking telephone pole. We stopped. Suddenly. Then we laughed about the whole thing. She called me the following day and we both agreed that things went to far. But we're close friends so it's bound to happen again and we both know it. Is it normal to have sex with you first cousin? I'll bet it happens a lot. So it must be normal. Yes?