content: No, it's for real. Like hair follicles, you're born with all that you'll ever have. As you grow older, and testosterone/estrogen starts flooding your body, your hair follicles will either become thicker and more prominent, or stay supple and fine, respectively. You don't actually gain more follicles, to grow a beard, for instance.  Similarly, you're born with all the teeth you'll ever have. This is why, when one falls out, your body doesn't just "grow" a new one. You only have so many tooth "buds" to grow, and they just get larger, and pushed through as you get older.