This bothers most girls. As their bodies become more used to hormonal ups and downs this hair growth subsides and may lighten. Girls should be advised not to shave. Hair will not grow back darker or thicker but shaving will result in a rough 'whisker' for a few days which will not appeal to the girl. If she is very self-conscious about hair growth, refer to a doctor or a licensed beautician.
Menstruation is a major source of curiosity for both boys and girls.
The list goes on. Wet dreams are a source of concern for boys. Some boys who do not know about ejaculation may try to stop the semen from coming out. This can result in an inflammation of the testicles - another reason to talk. During ejaculation, including during wet dreams, only one teaspoon of semen comes out.