Sexual ponderings...adult pointless announcements - NSFW

I find it interesting that we, as individuals & as members of society in general, find it difficult to view people separately from personal things we know about them, esp if they have unorthodox sexual proclivities. I include myself even though I try to be open-minded about most things.

A female teacher I knew was married to a man, they had a solid marriage, & she occasionally had sex with women. It didn't affect how I interacted with her, but the knowledge would surface in my mind.

Is prurient interest, of course to varying degrees, part of our human nature? Do our minds have involuntary titillating thoughts?