Not everyone’s blessed with a talented mind and a silver tongue. Plenty of important historical figures have struggled with a stutter, ranging from politicians like former Vice President Joe Biden and British Prime Minister Winston Churchill to artistic types like Marilyn Monroe and Lewis Carroll. This, however, raises the question: What causes the condition in the first place?

Contrary to popular belief, experts say that stuttering—which typically starts in kids between 2 and 5 years old—doesn’t stem from anxiety, SciShow Psych host Hank Green explains in the video below. Being shy or nervous can make stuttering worse, but research shows that people who manage their symptoms score about the same on anxiety tests as people who never stuttered.

Since individuals are far more likely to stutter if they have a family member who also stuttered, genetics likely play a part. Meanwhile, recent studies have found that chromosomal mutations may be involved, and that there are neurological differences between people who stutter and those who don’t.

Since kids’ brains are developing at the same time as they’re beginning to stutter, experts don’t know whether these physical differences cause stuttering, or if growing up with a stutter alters the brain. That said, treatment options are available for the roughly 3 million Americans with the speech disorder, ranging from therapy to self-help groups and medication.

To learn more about what causes stuttering—and how to overcome it—check out SciShow Psych’s video below.