Researchers at Washington University School of Medicine in St. Louis studied 3,546 female twins ages 18 to 29 and found environmental factors the twins shared, such as exposure to conflict between parents or alcohol use among peers in school, exerted the largest influence on initiation of alcohol use.

The study, published in the Alcoholism: Clinical and Experimental Research, found that females who had their first drink at an earlier age were more likely to develop serious alcohol problems.

"Even when genetic factors are most influential, they account for less than half of the influence on drinking behavior," lead author Carolyn E. Sartor, a post-doctoral research fellow at the School of Medicine, says in a statement.

"That's good news in terms of modifying these behaviors and reducing the risk of developing alcohol dependence. Genetics are not destiny and our findings suggest that there are opportunities to intervene at all stages of alcohol use."