Scientists prove that the smell of fear can be inherited through genes and then passed down through two generations



Mice taught to fear smells pass this information to their offspring



The fear apparently causes chemical changes in their sperm



This then alters the brains of their children causing them to fear the smell

Genetic: Mice taught to fear a certain smell pass this information on to their children through their sperm

The smell of fear can be inherited genetically and can be passed on for two generations, scientists have proved.

For the first time researchers at Emory School of Medicine in Georgia have shown that if mice are taught to fear a certain smell this triggers chemical changes in their sperm.

These changes then alter the makeup of their children and grandchildren's brains, causing them to fear the same smell.

If the same is true of humans it could completely change the way we think about adult behaviour, and how we treat conditions such as post traumatic stress disorder.

Kerry Ressler, professor of psychiatry and behavioral sciences, said: 'Knowing how the experiences of parents influence their descendants helps us to understand psychiatric disorders that may have a trans-generational basis, and possibly to design therapeutic strategies.'

During the study mice were taught to associate the smell of cherry blossom with a mild electric shock. After a short time the mice reacted fearfully even if they were just exposed to the smell.

Scientists then checked the mice's offspring and found that they also associated the odor with fear, despite never having been given an electric shock.

They concluded that the trait must have been passed down genetically as the fathers never met their offspring, meaning the behaviour could not have been learned.

This could completely change the way we think about conditions such as post-traumatic stress disorder

Post-traumatic stress attacks have been shown to be triggered by smells, and scientists fear that soldiers could pass this information on to their children causing them to suffer

The offspring were not more nervous generally, and only reacted to the same smell their parents had been taught to be wary of. They were also able to pick up on very small amounts of the smell and had a larger space in their brain dedicated to detecting odors.



The experiments also showed that the information can be passed down through the mother, and that it affects children whether they are conceived naturally or through IVF treatment.

The study concluded that 'ancestral experience before conception' could be an under-appreciated affect on people's behavior, especially where parents had been through a particularly traumatising experience, such as a war-zone.

Previous studies have shown that post-traumatic stress attacks can be brought on by particular smells and the fear is that soldiers could pass this fear on to their children, causing them to have similar attacks when they detect the same odor.













