"People used to think that it didn't matter, because a child represented a new beginning, with a fresh start. The reality is, we can now say with great certainty that the child doesn't quite start from scratch - they already carry over a legacy of factors from their parents' experiences that can shape development in the foetus and after birth. Depending on the situation, we can give our children a burden before they've even started life," said Robertson.

This includes a higher risk of metabolic diseases, such as diabetes and cardiovascular disease. The likelihood of conditions like anxiety and immune dysfunction can also be affected.

Robertson says current research is also showing that the fathers have a much greater role to play in this than previously thought.

"A few lifestyle changes by potential parents and improvements in the right direction, especially in the months leading up to conception, could have a lasting, positive benefit for the future of their child," Robertson said.

The research was published in the journal Science.

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