Neurodevelopmental correlates of paraphilic sexual interests in men.

The etiology of anomalous, or paraphilic, sexual preferences in men is unclear although a growing literature points to their prenatal neurodevelopmental ontogenesis. The present study explored whether this was also apparent in a community sample of 200 heterosexual men by examining their sexual fantasies using the Wilson Sex Fantasy Questionnaire (WSFQ) and several demographic and somatic neurodevelopmental markers, including sibling sex composition, handedness, maternal and paternal age at birth, second to fourth finger length ratios, and fluctuating asymmetry of finger lengths and wrist widths. Responses to the WSFQ were used to quantify the extent of paraphilic interest by computing a variance-quotient (or VQ) previously shown to differentiate paraphilic from conventional heterosexual males. High paraphilic scorers had a significantly greater number of older brothers, higher right-hand 2D:4D, and a trend for lower Edinburgh Handedness Inventory (EHI) scores compared to low-paraphilic scorers. Correlational analysis revealed a significant positive association of VQ scores with number of older brothers and significant negative associations with number of younger brothers and EHI scores (elevated paraphilic interests were correlated with elevated non-right handedness). Correlations between VQ scores and other variables were not significant. It is suggested that processes such as developmental instability and maternal immunity may play a role in variant sexual preferences among otherwise healthy heterosexual men.