Our parenting styles as well as our genes have a big impact on how our children turn out, a new long-term study has said, reports New Zealand Herald News.

Angry and aggressive parents are more likely to have children who are also angry and agro, even if the children aren’t biologically related to the parents - that is, they’ve been conceived with donor eggs and donor sperm. If biologically unrelated mums are cold and distant, the children were also more likely to be aggressive. If unrelated mums are depressed, the children were more likely to be depressed.

However, if biologically unrelated dads are depressed or cold and distant, there’s no detectable effect on their children, the study said.

The study looked at 888 IVF children born in the UK and USA between 1994 and 2002. The children could be split into five groups:

1. Those biologically conceived by both parents
2. Those biologically related to their mums and conceived with donor sperm
3. Those biologically related to their dads and conceived with donor eggs
4. Some children that were completely unrelated donor embryos
5. Some children that came from surrogate mums

Psychologist Gordon Harold, who led the study, said the argument over whether nature or nurture had the biggest effect of children had been investigated by many studies on twins or adopted children, but this research was the first based around children conceived by IVF. It meant the study could tell apart the environmental and genetic effects for mums and dads.

However, Professor Gordon, from Otago University, did say the results also showed children weren’t just products of their environments, or nurture. "What this paper is not saying is that genetic factors do not matter in human development. Absolutely not!" he said.