Fathers using cocaine might protect their sons from becoming addicted.
New studies are finding that some inheritance, like addiction, doesn't come down through the genes but through epigenetics - that's the process of certain genes being turned on and off.
Scientists found male descendants of rats who got a lot of cocaine did not show the same increase in motor activity as rats whose dads did not use coke.
Certain neuroreceptors in their brains had been turned off, leading to more resistance to addiction.
The findings were presented in San Diego at the Society for Neuroscience's annual meeting.