"There is very strong evidence that the male brain comes wired with a biological predisposition to attending to feet. But of all the male anatomical cues, the foot cue expresses itself with the greatest diversity of variations, suggesting that there might be something more to this anatomical cue than mere visuals. The foot is a classical example of a male sexual cue that gives rise to a kaleidoscopic variety of cued interests: pantyhose, stockings, heels, ankles, calves, sandals, high heels, socks, toes, boots, boot licking, foot bandages.
How does a man's specific interest in silky pantyhose or five-inch heels get formed? Following cue theory, during a man's critical period of sexual desire formation, his innate foot cue makes him more likely to pay attention to feet and makes him more receptive to foot-related stimuli. If through chance or culture he is then exposed to a strong foot-related experience—a woman sticking her foot in a thirteen-year-old's face or watching your first girlfriend slowly unroll her black stockings—then the foot-related details of the experience are more likely to get imprinted. Also increasing the odds of imprinting upon a foot-related stimuli are the strong odors associated with feet; odors and tactile sensations enhance the likelihood of imprinting upon a sexual experience.
There are multiple lines of evidence suggesting that the male foot cue is innate. The anthropologist Daniel Fessler found that men from a broad variety of societies consistently rate small female feet as more attractive than large feet. In contrast, women rated an average male foot size as most attractive. On erotic foot-focused websites, small feet are represented almost exclusively. Several cultures, such as the Chinese and Persians, historically practiced foot binding in an effort to make the feet physically smaller. Many American women habitually wear shoes that are too small for their feet.
However, there is one peculiar facet to the male interest in feet that remains unexplained. More than a century ago, Sigmund Freud was one of the first scientists to suggest that there was a link between a sexual interest in feet and submissiveness. At present, the nature of the foot-submissiveness connection remains a mystery, and the online data doesn't provide an explanation, just proof of the connection. Is there something about a strong submissive cued interest that makes the foot cue more prominent? Is there something about a strong foot cued interest that makes the submissive cue more prominent? Is there some kind of cross-wiring in the male sexual brain so that these two cues are more likely to be tangled together? Perhaps future neuroscience efforts will reveal the truth. But one thing seems clear: both interests seem to form very early in men in vastly different cultures (and eras!) suggesting there is indeed some kind of neural connection between the two."
source: Psycholog Today website, Mar 14, 2013, "Sexualpedia 7: Why Am I So Turned On By Feet?" by Ogi Ogas Ph.D.