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Earlier this week, I blogged about the risk of autism during pregnancy. But before anyone starts to blame mothers again, let me clarify that autism risk can also be affected by the fatherʼs health.

Men who smoke and drink are essentially exposing themselves to environmental toxins that could damage their sperm, that much is already known. But according to research presented earlier this week at the American Association for the Advancement of Science (AAAS) meeting in Boston, those defects can be passed down to children and persist even four generations on.

What is interesting here is that these changes are epigenetic chemical modifications that can switch a gene on or off, without altering the actual genetic sequence.

Thereʼs been some debate about whether epigenetic changes can be passed on to children but in recent years, scientists have suggested that epigenetics may explain some cases of autism where there isn’t a clear genetic component. For example, epigenetics could explain why older men have a higher risk of fathering children with autism the topic of a news story weʼll run later this week.

In this case, the researchers injected embryonic rats with a fungicide called vinclozolin, which is thought to disrupt the activity of some hormones. Vinclozolin altered genes in the ratsʼ sperm, and triggered overgrowth of the prostate, infertility and kidney problems. These alterations ― and problems ― were still present in rats four generations on.

Granted, the researchers gave the rats vinclozolin at concentrations far higher than any person would reasonably be exposed to, but the most intriguing piece here is that the effects of these toxins are heritable and persist for generations.