Background: Given the importance of parenting for the child's early socio-emotional development, parenting perceptions and behaviours, and their correlates, should be assessed as early as possible in the child's life. The goals of the present study were 1) to confirm, in two parallel population-based samples, including a large sample of twins, the factor structure of a new self-administered questionnaire assessing both parents' specific parenting perceptions and behaviours toward their 5-month-old infants (i.e., parental self-efficacy, perceived parental impact, parental hostile-reactive behaviours and parental overprotection), 2) to identify the specific risk factors associated with the negative side of these parenting dimensions, 3) to document the genetic-environmental etiology of these parenting dimensions through the twin method. Methods: Parents (2,122 mothers and 1,829 fathers) of 5-month-old infants, and parents of 5-month-old infant twins (510 families) completed the questionnaire (28 items). The data were submitted to a series of confirmatory factor analyses. The contribution to parenting of a variety of risk factors was examined in the two samples using regression analyses. A series of quantitative genetic analyses were performed to quantify the different sources of variation in parenting. Results: A consistent factor structure was found across informants and across samples. There were significant mean differences in parenting between mothers and fathers, as well as between parents of twins and parents of singletons. A differentiated pattern of association with risk factors was found for each dimension of parenting. The twin analyses revealed that shared environment accounted for each parenting dimension. Maternal hostile-reactive behaviours were also moderately related to genetic factors in the child and this association was mainly mediated by the infant difficultness. Conclusions: The overall pattern of results was consistent with Belsky's (1984) view of parenting as multiply determined. The longitudinal follow-up of these families should provide the means for testing developmental models about the determinants and outcomes of these parenting dimensions.