Here's why:
* Babies are born with very little melanin: Melanin is the pigment that gives hair its color. Babies are born with very little melanin, which is why most babies have very light hair, sometimes even appearing white or blonde.
* Hair color develops over time: As babies grow, their bodies start producing more melanin. This can cause their hair color to darken, eventually becoming brunette, blonde, red, or another color.
So, while a baby might eventually become brunette, they are not born with brunette hair.