A genetic mutation and environmental factors before and after birth can increase the risk of suffering from brittle bone disease decades later, researchers said on Tuesday.

The gene regulates the amount of human growth hormone, which plays a vital role in the development of healthy bones, that is generated by the body.

The illness, also known as osteoporosis, occurs in about one in three elderly women and one in 12 older men.

“It is the first time the gene has been linked to osteoporosis in humans,” Professor Cyrus Cooper of the University of Southampton told Reuters in an interview.

The genetic defect coupled with poor nutrition in the womb and early in life as well as maternal smoking raise the odds of a child suffering from the disease as an adult, he said.

Osteoporosis, which causes a loss in bone mass, is most common in older women after the menopause when levels of the female hormone estrogen drop.

Smoking, lack of exercise, excessive alcohol consumption, low levels of calcium and vitamin D, and being thin are risk factors. The hip and vertebrae are the most frequent sites of fractures in people suffering from the bone-weakening disease.

Cooper and his colleagues made their discovery by examining a genetic database. About 15 percent of the population has the mutation in the GH1 gene.

By studying 300 men and women born in Britain in the 1920s and 1930s they also found that even if a person had the genetic defect, good nutrition in the womb and early in life seemed to counteract any negative effect.

“Although there is a strong genetic contribution to skeletal growth, our work also suggests that the impact of an adverse genetic makeup might be minimized by improving the environment in the womb,” Cooper said.

“For example, paying attention to maternal nutrition, reducing maternal smoking and avoiding heavy physical activity by mothers in late pregnancy,” he said.