Mother and child ADHD symptoms both have a negative effect on parenting. Little is known about how these characteristics interact. In a recent paper, we reported two studies that suggested that maternal ADHD ameliorated the negative effects of child ADHD on negative parenting supporting a "similarity-fit" hypothesis. The aim of the current paper is to extend this analysis to a sample of mothers and fathers. The study examined the association between child and adult ADHD symptoms on child-specific parenting practices in 278 mothers and 85 fathers from a population-based sample of school-age children. As in the previous study, high levels of ADHD symptoms in mothers ameliorated the negative effects of child ADHD on parenting--supporting the "similarity-fit" hypothesis. Fathers demonstrated the opposite effect with high levels of ADHD exacerbating the effects of child ADHD--supporting a "similarity-misfit" hypothesis. The study confirms the important role played by parental ADHD symptoms in parenting while highlighting differences between mothers and fathers in this regard.