Why is there no sign of facial hair in Pi's face?

Men typically start developing facial hair in the later years of
puberty or adolescence, between seventeen and twenty years of age, and
most do not finish developing a fully adult beard until their early
twenties or later. This varies, as boys may first develop facial
hair between fourteen and sixteen years of age, and boys as young as
eleven have been known to develop facial hair.(source : Wikipedia)

Pi is only 16 years old during the course of the story, and not every 16 year old boy has facial hair.