A foot fetishist can be sexually aroused by viewing, fondling, licking, tickling, sucking, punishing, sniffing or kissing the feet and/or toes of another person. The fetishist response to the foot is the same or very similar to arousal at seeing genitals.
One explanation, advanced by neurologists, highlights the fact that the feet and the genitals occupy adjacent areas of the somatosensory cortex(in the brain), possibly entailing some neural crosstalk between the two.
Another possible theory behind foot-fetishism could be rooted in the idea that a persons feet are usually hidden, much in the same manner as genitalia. Suddenly exposed feet could hypothetically produce a feeling of pleasure in the same way that any intimate body part could. A female, in the initial stages of undress for a romantic encounter, usually removes her shoes first. Perhaps launching a visually erotic chain reaction, allowing the male to perform during reproduction.