There is a relationship between the size of male genitalia and genetics. There may be significant individual differences in the size and length of the penis, which are mainly related to factors such as race and genetics. In addition, genital size is also related to their nutritional status, whether they are obese or not, testicular development, endocrine sex hormone levels, especially androgen levels, and many other factors. In general, the Asian adult male penis in the state of erection, can reach 8 centimeters, the state of weakness to reach 4 centimeters is normal, as long as the penis can be erected during sex, can maintain sufficient hardness and can be ejaculated within a certain period of time is normal. However, if it is less than this length, it can be called a short penis. There are many reasons for a short penis, and there is also a relationship with heredity. If a person is obese or suffers from some physiological diseases, such as testicular inflammation, testicular hypoplasia, etc., it can also lead to symptoms of a short penis. If the value is lower than the normal value is more, we should go to the regular hospital urology department in time. Check whether there are other aspects of deformity, if necessary, to consider surgery to correct.