Teens who are dependent on marijuana and alcohol struggle to achieve hallmarks of adult success, such as graduating from college, getting married, having a full-time job and earning a good salary, a new study finds.

Researchers at the University of Connecticut tracked 1,165 study participants, starting at age 12. They checked in on them at two-year intervals, until they were between 25 and 34 years old, HealthDay reports. Most of the participants had a grandparent, parent, aunt or uncle with an alcohol problem. Marijuana and alcohol dependence appeared to have a more severe effect on young men.

“Parents should try to delay their children’s onset of use as much as possible,” said researcher Victor Hesselbrock. “If you can push regular use back well into adolescence, the kids do a lot better.”

The study was presented at the annual meeting of the American Public Health Association.