WASHINGTON (AP) — Obese mothers tend to have kids who become obese. Now provocative research suggests weight-loss surgery may help break that unhealthy cycle in an unexpected way — by affecting how their children’s genes behave.

In a first-of-a-kind study, Canadian researchers tested children born to obese women, plus their brothers and sisters who were conceived after the mother had obesity surgery. Youngsters born after mom lost lots of weight were slimmer than their siblings. They also had fewer risk factors for diabetes or heart disease later in life.