Smoking weed is often seen as an indulgence reserved for the young and the reckless: kids get high, in the popular imagination, but by and large their parents don’t.

But new federal data show a stunning reversal of that age-old stereotype. Middle-aged Americans are now slightly more likely to use marijuana than their teenage children.

The research, released this week by the Centers for Disease Control and Prevention, found that only 7.4 percent of Americans aged 12 to 17 years old smoked marijuana regularly in 2014, a 10 percent decline since 2002. But 8 percent of 35 to 44 year olds used marijuana regularly in 2014, surpassing use among teens for the first time since at least 2002. (Survey data prior to that year aren’t directly comparable, as the methodology changed.)

And it’s not just middle-aged folks who are indulging more often. Since 2002, regular marijuana use among Americans age 45 to 54 has jumped by nearly 50 percent. Among those ages 55 to 64, it’s jumped by a whopping 455 percent.

And among seniors, age 65+, monthly marijuana use is up 333 percent since 2002.

According to the authors of the study, if trends continue like this, marijuana use among 50- and even 60-somethings could be higher than use among teens in a few years.

There is a key factor that could explain rising marijuana use rates among the middle-age-and-up crowd. The growing prevalence of medical marijuana, which is now allowed in 25 states and Washington, D.C. Older Americans are increasingly turning to medical pot to treat some of the common ailments of old age, like sleeplessness, aches and arthritis pain.