His eldest sister (half-sister) just got married, and his dad looked really upset. I thought that was strange, because he was acting like a jealous sim. I thought "don't tell me he had the hots for his stepdaughter!?!" I checked his profile from her, and sure enough he was listed as "romantic interest". Ew, that's creepy.
But I guess it's ok, because they're not related by blood. But hey, he married her mom when she was a child (when they moved from xbox to my pc), so he's practically her dad.