Do you let sims with common ancestors that the game no longer considers related be romantic?

I don't think i would like it as in game i would know they where related, but if they truly loved eachother then i wouldn't stand in their way, as it's no problem geneticly between 2'cousins.
In real life i have cousins i have never met, and any children from our generation would be oblivios to any relations until it was a bit late (HUM) I also have so much 2'nd cousins that i have given up in trying to find out if i am related to and how. The fact that i don't "sleep around" is probably a blessing in this situation :D