A foot fetish sort of works its way into your brain over time. The synapses for feet and sexual attraction are extremely close to each other, so when you do things like, hold someone’s feet during sex, or give them a foot rub during foreplay, there’s a chance your brain may start making that connection that feet are an erotic thing. For me, it started after being married for a few years, and she just sort of flexed her toes during sex in such a way that it gave me goosebumps, in a good way. Granted I’d been giving her foot rubs for a few years by that point…but oh…my god. When it clicked that it was a turn on for me, it was a game changer.