Chemical changes caused by cocaine may be passed on to the next generation, a new study of rats suggests. The changes cause male offspring to find the drug less rewarding, according to The Wall Street Journal.

The study indicates the chemical effects of cocaine can change how genes are controlled in succeeding generations, without changing the genes themselves, the article notes.

The researchers studied male rats that used large amounts of cocaine, who were mated with female rats not exposed to the drug. Once the female rats were pregnant, the males and females were kept separate, and the males had no role in rearing the rat pups. When the offspring of these pairs were offered cocaine, the male offspring were not very interested in the drug, while the females were.

Compared to offspring of males not exposed to cocaine, the rat pups whose fathers were exposed took the drug less readily and took less cocaine overall. The sons of cocaine-using male rats did not work as hard to get the cocaine as the sons of non-exposed males. This suggests they found the drug to be less rewarding, the researchers said.

“To our surprise, the male offspring of dads who took cocaine did not like cocaine as much,” said lead researcher Chris Pierce of the University of Pennsylvania. “They took less cocaine and they liked it less.”

The findings were presented this week at a meeting of Society for Neuroscience.