Oh yeah, I'm gonna echo one of Slab's sins. When I was playing the game back then I also always picked infertile. I've never sired/birthed not one child with any of my Steeles.
I just... I can't do kids nowadays, especially as time went on I've seen a lot of negativity in regards to the PC being a parent and all in TiTS in older threads. It really brought me down. That along with the fear of having kids I gained overtime to the point I want to actually remove that ability irl (As extreme as it is, but Sterilix doesn't exist irl so what else is there), and I'm not into it whether it's being pregnant or siring them in fantasy either. (It's very similar to my phobia of spiders and the like, which is why the Bothrioc Quadommes freak me out as well. No offense to Nonesuch) I just don't like making the PC have kids anymore. Pregnancy isn't my thing, nor is being the U L T I M A T E S T U D lol. I don't really self-insert into the PC, but with what I CAN control, the lack of actually wanting kids is one of them, so I try to avoid that as much as I possibly can.
I don't mind other NPCs getting pregnant or siring babies with someone else, but I just don't want to be the parent of one. Cuntsnakes are a huge grey-area though, but those are parasites, not like anything that involves any real big commitment, so I'm cool with those.