A. According to the American Academy of Pediatrics (AAP) , at this age these actions are completely normal. It is common in many families that kids will see each other naked at these young ages. Bath time, changing clothes. It is a healthy and normal part of development. If he is showing interest it is the perfect opportunity to start important conversations to explain the differences and applaud their curiosity about the opposite sex. Between the ages of 3 and 5 it is a great time to start conversations about personal safety and private parts. This is the time to teach them their body is special and only belongs to them!