Dad's health 'sins' may be visited on his grandchildren

Over the past decade, a growing body of scientific evidence suggests a father’s life experiences, including food choices, drug or alcohol use, exposure to toxins, and even stress can affect the development and health of not only his future children but also his grandchildren, long before any of his offspring are conceived.

Scientists have long known the transmission of inherited traits involves genes, DNA, and certain molecules that attach to DNA and act like a dimmer switch to turn gene expression up or down. But they had no explanation for how events that affect the father or grandfather, referred to as “environmental memories,” are transmitted down the generations. Now, researchers at McGill University in Montreal believe histones, a type of protein distinct from DNA, may be the answer.

The researchers created genetically modified mice by slightly altering the biochemical information in the histones during sperm cell formation. The scientists used the types of modifications that are most affected by things such as food, drugs, and stress in both mice and humans.

The offspring of the altered mice suffered dire consequences such as birth defects, limb, skeletal and facial deformities, skin problems, and stunted growth. Many of the mice died shortly after birth. The researchers were most surprised to find the abnormalities still present two generations later and that the problems extended to the grandchildren of the altered mice, even if the parents didn’t inherit the abnormality.

Even though this study involved mice, lead author Sarah Kimmins told CBC News she is confident humans would react in the same way because mice and humans have very similar histone proteins in their sperm.

Physicians usually focus efforts to prevent birth defects on the mother’s health before conception and during pregnancy, but this study highlights the role fathers play in the health of their children and even grandchildren, Kimmins said.

Former scientific studies have shown an association between a man’s diet or smoking habits and abnormal growth or health problems like cardiovascular disease transmitted down generations.

“Since chemical modifications on histones are susceptible to environmental exposures, the work opens new avenues of investigation for the possible prevention and treatment of diseases of various kinds, affecting health across generations,” Kimmins said. This study should serve as a reminder to fathers to be diligent protectors of their germlines, she added.

The researchers are now conducting studies with a group of men in Africa and another group in Toronto to see if diet or exposure to substances like alcohol produce any changes in sperm.