You’re hanging out, having a smoke, and feeling good—then a random thought crosses your mind: is all this weed affecting my balls?

There’s a lot of talk out there about whether cannabis impacts sperm count, fertility, or even the health of your crown jewels.

With so many opinions—some saying it’s harmless, others warning you to be careful—it’s tough to know what’s true. So let’s get real and clear up what’s actually happening between weed and your boys downstairs.

A recent study published by the American Journal of Epidemiology showed that men who smoke marijuana at least once a week have a 33% lower sperm count than men who do not use marijuana.

“The sperm from marijuana smokers were moving too fast too early,” said lead researcher Dr. Lani Burkman. “The timing was all wrong. The sperm will experience burnout before they reach the egg and would not be capable of fertilization.”

Though this study suggests that marijuana users have lower sperm counts, it also mentions that other factors such as caffeine use, drug use, and lifestyle choices can contribute significantly to lower sperm counts.

Yes, you can technically still donate sperm if you smoke weed.

Most sperm banks, like the San Diego Sperm Bank, don’t disqualify donors for marijuana use and don’t specifically test for cannabis. However, they do perform initial and routine semen analyses to check overall sperm health.

And, using cannabis, especially more than once a week, can impact sperm quality. So, while smoking weed won’t necessarily stop you from donating, it could affect the quality of your donation.

If you’re planning to donate, it might be worth taking a break from cannabis for a while to keep your swimmers in peak condition.

A 2012 study conducted by Cancer.org found that of 455 men studied, 163 of the men were diagnosed with testicular germ cell cancer and 292 of the men were not. The study goes on to report that men who reported a history of recreational marijuana use were nearly 50% more likely to develop testicular cancer.

American males between the ages of 16-25 are most likely to smoke marijuana, and men between the ages of 16-30 are most likely to develop testicular cancers—perhaps cancer, in this case, is more a function of age than marijuana use.

Again, this study does not definitively conclude that marijuana use is a direct cause of testicular cancer, but the statistical connection is significant. Some suggest that vaporizing as a form of marijuana consumption can help reduce some of the “cancer-causing” effects of smoking.

Yes, there are a number of studies out there that will make you believe that marijuana use is your package’s worst nightmare. There is certainly some correlation between marijuana use and testicular issues, but in all cases, it appears that overall lifestyle choices play a bigger part in any issues.

If you are a marijuana smoker, and you are concerned about your balls, you might first start by wearing boxer shorts instead of briefs.  Tighty whiteys have been known to reduce sperm counts as well – let’s point the finger that way before we believe accusations against weed.