It may be possible to learn your parents' fears—without ever experiencing the relevant threat. Researchers taught mice to fear a cherry blossom smell, then looked at the creatures' sperm. A portion of DNA tied to the scent was particularly active, and two generations of descendants were found to be "highly sensitive" to the smell. They tried to avoid the scent even though they themselves had never previously been exposed to it; what's more, their brain structures were altered, the BBC reports.
"The experiences of a parent, even before conceiving, markedly influence both structure and function in the nervous system of subsequent generations," researchers said in the Nature Neuroscience report. The findings, says an expert, are "highly relevant to phobias, anxiety, and post-traumatic stress disorders." But some outside researchers say the findings need a clearer explanation, Nature notes. "The claims they make are so extreme they kind of violate the principle that extraordinary claims require extraordinary proof," says one. Scientists began researching the matter after noticing a cycle of addiction and neuropsychiatric issues among inner-city generations, Nature reports.