Many parents do not understand what is a sign of development in their children, and often mistakenly believe that a girl’s breasts are above the level of her chest to be called developed. In fact, when a child begins to develop, the breasts are flat in appearance and can be tender to touch and have a very small nucleus under the skin. The start of sexual development in boys is often overlooked by parents, many of whom think that the change of voice and seminal emission is sexual development, but in fact that has already reached the peak of development. Normal male sexual development usually begins when the testicles become larger, and the growth of the testicles from 4 ml to 5 ml is considered by medical science as a sign of the beginning of normal male sexual development. If you find an abnormality, you should consult your doctor in time to determine the indications and treat it in time. You should never have the mentality of waiting and delaying your child’s growth for various reasons, causing lifelong regrets.