Nearly all self-touching behavior is normal, and as a general rule, parents have nothing to fear from their child's sexual exploration. However, there are times when touching could be a sign of a larger issue.
Kids pull on their earlobes when their ears hurt and rub their eyes when they're sleepy. In the same way, they often tug at, rub, or touch their genitals in response to pain or discomfort. Consistent touching could be a sign that your child has an infection, skin irritation, or injury. If there is redness, swelling, or any visible changes to your child's genital area, call your pediatrician immediately.
Masturbation and other kinds of genital touching are common comfort-inducers in children. If your child's touching becomes so prevalent that it gets in the way of other, normally enjoyed activities—like playing with toys or listening to a story—it could be a symptom of depression or intense worry. Try to determine what in your child's life may be causing such emotional distress; is there a new baby in the house, or has he or she started at a new school? If your child is old enough to have a conversation with you, ask questions, and try to get at the root of the problem.