Experiments showed that a traumatic event could affect the DNA in sperm and alter the brains and behaviour of subsequent generations, BBC reports.  

A Nature Neuroscience study shows mice trained to avoid a smell passed their aversion on to their "grandchildren".

Experts said the results were important for phobia and anxiety research.

The animals were trained to fear a smell similar to cherry blossom.

The team at the Emory University School of Medicine, in the US, then looked at what was happening inside the sperm.

They showed a section of DNA responsible for sensitivity to the cherry blossom scent was made more active in the mice's sperm.

Both the mice's offspring, and their offspring, were "extremely sensitive" to cherry blossom and would avoid the scent, despite never having experienced it in their lives.

Changes in brain structure were also found.

Prof Marcus Pembrey, from University College London, said: "It is high time public health researchers took human transgenerational responses seriously.