Do you let sims with common ancestors that the game no longer considers related be romantic?
Most,if not all of us probably already know that the game doesn't consider sims related after a generation or 2 and a sim can be attracted to e.g their 2nd cousin. When things like this happen, do you...
I try to play without altering any born in game sims, so if they both have traits I want passed on I get them together to make sure those traits get into the next generation. Kinda like dog breeding... hahaha