Here's why:
* Hair growth is determined by hormones. Testosterone is the primary hormone responsible for facial hair growth in men. Women have much lower levels of testosterone, which is why they don't naturally grow facial hair.
* Shaving only removes the hair at the surface. It does not affect the hair follicles, which are responsible for producing new hair.
* Shaving can make hair appear thicker. This is an optical illusion. When you shave, you are cutting the hair off at a blunt angle. This makes the hair appear thicker and darker when it grows back.
If a girl notices an unusual amount of facial hair growth, it's best to consult a doctor to rule out any underlying hormonal imbalances.