In the current study, we examined parent gender differences in feelings (negativity and positivity) and perceptions of child behavioural and emotional problems in adoptive and biological parent-child dyads. In a sample of 85 families, we used a novel within-family adoption design in which one child was adopted and one child was a biological child of the couple, and tested whether the links between parent feelings and child maladjustment included effects of passive gene-environment correlation. Parents reported more negativity and less positivity as well as higher levels of externalizing behaviour for the adopted child compared to the non-adopted child, although effect sizes were small and no longer statistically significant after correcting for multiple comparisons. Fathers and mothers did not differ significantly in their reports of positive and negative feelings towards their children or in regard to child externalizing and internalizing behaviours. The correlations between parental negativity and positivity and child externalizing and internalizing were similar for fathers and mothers, and for adopted and non-adopted children. The findings suggest similar parent-child relationship processes for fathers and mothers, and that genetic transmission of behaviour from parent to child does not account for the association between parental warmth and hostility and child-adjustment problems. (Contains 3 tables.)