Small or large, a woman's breasts can provide enough milk for her baby. Some people like big penises or big breasts. However, being attractive, cool, hot, cute, sexy, masculine, or feminine doesn't depend on how big breasts or penises are. During puberty, things happen inside the body, too. During puberty, most girls start having periods.
Most boys start having wet dreams.
And girls and boys begin having a lot more thoughts and feelings about sex. Sometimes they get really turned on. Important changes happen inside the body by the time wet dreams and periods begin. These changes mean that the reproductive system is maturing. As boys mature, they begin producing sperm.