Toxoplasma gondii affects animal behavior, I don't think it's a stretch to think it (or something similar) could affect humans in some way we haven't measured yet.

I think it’s very common for parasites to affect their host’s behavior.

If you find this topic interesting, I recommend the book “Parasite Rex”

I think this is widely speculated already, right? It is just hard to measure human behavior. I mean one of the proposed effects on Wikipedia is a reduced aversion to cat urine. But obviously there is a correlation/causation question there, haha,