The supposed “gateway effect” of marijuana, whereby teens who smoke pot move onto harder drugs, is largely overblown, according to research from the University of New Hampshire and printing in the Journal of Health and Social Behavior.

Anti-drug groups frequently sited the potential for pot-smoking teens to move onto hard drugs in their “Just Say No!” campaigns back in the 1980s. Now, however, a study by researchers at the University of New Hampshire in Durham shows that this gateway effect is only present among teens who experience significant stress or unemployment. In fact, punitive measures toward marijuana use could actually lead to harder drug use.

“Employment in young adulthood can protect people by ‘closing’ the marijuana gateway, so over-criminalizing youth marijuana use might create more serious problems if it interferes with later employment opportunities,” said one of the study’s lead authors, Karen Van Gundy, PhD.

What’s more, the modest gateway effect noted among stress-out and unemployed teens essentially disappears by the time they turn 21. The only predictor that a person who smokes pot will go onto use harder drugs is race, said the researchers: White kids were mostly likely to move onto other drugs, while black teens were the least likely.