Two of my sims are suddenly gay and in a relationship with each other

"So_Money;c-16942077" wrote:
Sooooo ... Back to the original topic, I haven’t seen this occurring randomly. And I’ve logged 150-ish hours in the game. I remember reading somewhere that sims have a hidden gender preference and that it is possible, but I’ve seen no evidence of it.

I haven't seen it much, either. My sims mostly stay on the path I set them on.

There is a hidden gender preference system though, so if you don't sort of point your sims far enough in the intended direction they might start experimenting.