Sure, it can make your kid’s teeth crooked. But they’d probably need braces anyway. In the meantime, it’ll boost their immunity and cut their chances of developing allergies! A study of over a‑thousand kids in the journal Pediatrics found those who sucked their thumbs for years were less likely to develop allergies as they grew. Because kids’ fingers are gross germ factories! But by ingesting germs in small amounts over time, they built a tolerance to things like pollen, pet dander, and dust. And if kids are thumb-suckers AND nail-biters, they get an even bigger immunity boost!