Pregnant women who gorge on fatty foods may increase the chances of their daughters and even grand-daughters developing breast cancer in later life, the Daily Mail reported.
Researchers believe eating an unhealthy diet can permanently alter the cells of an unborn baby - and future generations.
Scientists at Georgetown University in Washington DC used rats for their study.
While the findings have not been confirmed in humans, lead author Sonia de Assis said: "What a mother eats or is exposed to during pregnancy can increase her daughter’s breast cancer risk.
"This study is important because it may help our understanding of the origins of some breast cancers."
The researchers believe it could explain why breast cancer tends to run in families yet most cases are not genetic - they are not linked to any known mutations, the Mail said.