There are four main reasons for a small penis: 1, genetic factors, because the national penis is really smaller than the European, American and African races, while the father’s heredity is also very important. 2, testicular secretion of androgens, if androgen abnormalities can also lead to abnormalities in the development of the penis, resulting in smaller penises. 3, obese children have a higher level of estrogen in their bodies, which leads to the development of the child’s penis is relatively small. 4, and there is also a kind of Invisible penis, most of the penis is hidden in the patient’s fat, this situation can be corrected through surgery, in fact, the penis itself can still be the volume.