We investigated whether a sexual preference for smoking can be related to past experiences of parental smoking during childhood, as predicted by the theory of sexual imprinting, but also by sexual conditioning theory. In a sample of over 4000 respondents to five Internet surveys on sexual preferences, we found that parental smoking correlates with increased attraction to smoking in self-reported hetero- and homosexual males. Maternal smoking was associated with an increase in attraction to smoking both in hetero- and homosexual males, while paternal smoking was associated with an increase in attraction to smoking only in males who prefer male partners. We could not explain these findings by considering other factors than parental smoking habits, such as possibly biased reporting, indicators of a sexually liberal lifestyle or phenotype matching. Our data are consistent with the hypothesis that sexual preferences are acquired early in life by exposure to stimuli provided by individuals in the child's environment, such as caregivers. The sex specificity of the parental effect is consistent with sexual imprinting theory but not with conditioning theory.