Nurture, rather than nature influences aggression in children, finds a new study.
The study compares genetically related and genetically unrelated children born to parents using in-vitro fertilisation (IVF) to examine the idea that depression and anti-social behaviour are primarily influenced by genes.
"Associations were found between parent and child symptoms of depression and aggression among parents and children who were genetically related, but, crucially, also among parents and children who were not genetically related," Stuff.co.nz quoted University of Otago's Professor Gordon Harold, who led the research, as saying.
"While common genetic factors such as genes passed on from parents to their biologically related children may explain this association in the first of these groupings, they cannot explain associations in the second grouping as parents and children are not genetically related.
"This suggests that the rearing environment children experience may explain why symptoms are passed on from one generation to the next where common genetic factors cannot account for this transmission process."
Prof Harold, who is head of the university's centre for research on children and families, said the study found that parents who were hostile towards their children promoted increased levels of aggression in the children.
"This finding has significant implications for all parents - including those who are not genetically related to their children such as adoptive parents and genetically unrelated parents of IVF children.
"Rather than blame children's behaviour solely on the genes passed on from a biological parent to a child, look at the environments that children live in to understand better why some children develop behavioural problems while other children do not."
The study involved 1000 families with children aged between four and six years from the United Kingdom and the United States over a three-year period.
The study appears in the international journal Psychological Medicine.