A father’s smoking habits may harm the brains of his children and even grandchildren, a study on animals suggests.
Scientists found evidence that nicotine exposure causes chemical changes in key sperm genes.
For the study, male mice were given drinking water laced with low doses of nicotine during the stage in life when their sperm develops.
The animals were then bred with females that had never been exposed to nicotine.
While the fathers remained normal, offspring of both sexes displayed symptoms of hyperactivity, attention deficit, and mental inflexibility.
Females from the new generation in turn gave birth to male offspring with less pronounced but still significant mental impairment.
Analysis revealed evidence of “epigenetic changes” – alterations that affect gene activity – in the sperm of the original nicotine-exposed mice.
Dr Pradeep Bhide, from Florida State University in the US, said: “The fact that men smoke more than women makes the effects in males especially important from a public health perspective.
“Our findings underscore the need for more research on the effects of smoking by the father, rather than just the mother, on the health of their children.”
The findings are reported in the journal Public Library of Science Biology.
Dr Susanna Roberts, from the Institute of Psychiatry at King’s College London, said: “Despite the interesting results, it is difficult to extrapolate the importance of these effects in humans, where the causal pathways to behaviour and influences on biology are immeasurably more complex.
“Solid replication and further research in humans is needed before the implications are fully understood.”