So already I've slapped the "this guy is a baby" theory right out of the air. Now, even though I haven't been a baby for a quarter of a century, that hasn't stopped me from sucking my thumb the entire goddamn time. But even I'll admit that it's weird to see a grown-up with his or her thumb in their mouth, because not too many grown-ups are comfortable with being compared to infants. I really can't argue with that, especially since I just spent the last paragraph talking some major shit on babies. But I'll still find myself wondering "what gives?" Why was I left behind when most everybody else I know kicked the habit before turning six? It turns out that research on that very subject is hard to come by from any reputable source. For instance, WebMD says that one in five children will suck their thumb or finger past age five, right around the time that teasing from your peers turns from playful to "Holy shit, kids can be fucking assholes."
It's okay. They have testicles that are ripe for a kicking.
Teasing alone is enough to deter anyone from wanting to admit they're a thumb sucker. So if you are afraid to admit it as a child, odds are you won't be thrilled about owning up to it as an adult, either.
In addition to WebMD, there's also a website dedicated to thumb sucking adults, with some facts and a FAQ section. Though it's citing statistics that I can't seem to confirm, and it kind of looks like a serial murderer's manifesto. There's even a subreddit, because throw some random words together and guess what? There's a subreddit for it.
But none of these sites seem to give an official reason for it, other than "It's calming and helps you relax." While true, that doesn't help me understand myself any better. So that leads me to two conclusions: Either adults are afraid to admit to they are thumb suckers, or I'm one of the only people who does it. For the sake of this article, I had to do some more digging.
Here's what I was able to find.