Multiple factors determine handedness including genetics, prenatal stress and post-natal environmental conditions. Atypical handedness, whether manifest as increased sinistrality or decreased strength of lateral preference, has been noted in a wide variety of populations with neuropathology. Those with atypical sexual preferences, specifically paedophilia, also manifest reduced rates of right-handedness. This paper uses the largest sample of phallometrically assessed men to date to establish the pattern of atypical handedness in paedophilia. Specifically, whereas prior research has largely characterized participants dichotomously as right-handed or non-right-handed and/or used self-report of writing hand, this paper expands upon such reports by using the Edinburgh Handedness Inventory's laterality quotient. Participants' handedness and phallometrically assessed sexual preference were analyzed both as continuous and categorical variables, and the responses of those scoring in the range of ambiguous-handedness were evaluated to ascertain whether they were ambiguously handed or more accurately described as mixed-handed. Results indicated those producing scores in the range of ambiguous-handedness demonstrated response patterns consistent with ambiguous-handedness, rather than mixed-handedness. Paedophiles demonstrated high rates of non-right-handedness primarily manifested as sinistrality, whereas those who had a sexual preference for pubescent children evidenced increased ambiguous-handedness. Results support a view of ambiguous-handedness as less pathological than previously hypothesized, and of a neurodevelopmental origin of paraphilic sexual preferences.
Keywords: Handedness; Laterality; Paedophilia; Phallometry; Sex offenders.