Smoking dads – your habit may be putting your kids at risk for leukemia, reports Reuters.

Australian researchers recently discovered a 15 percent increased risk for developing leukemia in children whose fathers were smokers, according to the news source. The study’s authors analyzed the family situations of approximately 400 children with acute lymphoblastic leukemia (ALL) at the Telethon Institute for Child Health Research. The information was compared to the families of 800 healthy children in the same age bracket.

The study revealed that the mother’s smoking history did not affect her child’s risk of developing ALL; however, dads who were smokers around the time that conception occurred increased their child’s risk by 15 percent. Children whose fathers were heavy smokers – smoking a minimum of 20 cigarettes every day – had their risk increase by nearly 45 percent, according to the news outlet.

Scientists reportedly found the connection in the father’s sperm.

“Tobacco smoke is full of toxins, so it’s not unlikely that you’d have damage [in the cells that produce sperm],” Patricia Buffler of the University of California, Berkeley, told Reuters.

Dr. Elizabeth Milne, who led the study, noted that “sperm containing DNA [damage] can still reach and fertilize an ovum, which may lead to disease in the offspring.” She also emphasized that “the causes of ALL are likely to be multifactorial, and our findings relate to just one of the possible contributing factors.”

ALL is the most common cancer in children. Although it only affects a minuscule percentage of kids, more than 1,000 die from the disease each year.