The issue of childhood sexuality is controversial, and one which makes many people uncomfortable. But, although childhood sexuality is very different to that of the mature adult, there is little doubt that humans are sexual beings from birth, and even before: boy babies can have erections while still in utero, and some boys are born with an erection. Toddlers, and even babies as young as three to five months old might touch their genitals. Parents can be assured that this activity is quite normal, and that the child finds it soothing and relaxing.
The ability to produce sperm may take another year or two. These changes are accompanied by a surge of interest in sex. During this period, boys gain further experience with masturbation: about half of all boys have masturbated to orgasm by age 13. Because preadolescents tend to spend time mainly with others of their own sex, it is not uncommon for early sexual exploration to occur with other boys. By age 12 or 13, some boys will have started dating and "making out" with girls, but overt sexual activity with the opposite sex is still unusual.