The study by Emory University in Georgia, suggests that a fear of heights, for example, can become hardwired into the genes.
In experiments, researchers made mice fear certain smells by delivering mild shocks to their feet. A group of mice were trained to fear the smell of acetophenone, a common fragrance in soap and perfume, over three days.
They were allowed to mate ten days later.
Results showed that the offspring of the trained mice were startled by the smell of acetophenone, even though they had never encountered it before.
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Analysis found that when the grandparent mice were trained to fear acetophenone, the noses of their children and grandchildren all had more M71 neurons, the cells containing a receptor that detects the chemical, 'The Times' reported.
Another experiment by Brian Dias at the Ressler Lab at Emory University which used in-vitro fertilisation and the sperm of the affected mice, led to the same results.
The paper will be published in the journal Nature Neuroscience.