Brief Answer: Depends on physical presentation of genitals now Detailed Answer: Hello sir/ma'am and welcome. Thank you for writing to us. The penis of a 13 year-old child when not erect, in a shriveled state can appear to be small, but that does not necessarily mean that it has not developed or grown. But, if indeed the penis has not changed in size from the time of birth till not, then there could be a possible hormonal imbalance. The most important thing would be to check on the testes. May I ask if both your sons testes have descended? I would only be mildly worried if your son has undescended testicles or a growth problem since birth. Looking forward to your kind reply. If there has been a growth defect since birth, then this could be a different problem all together. I would recommend you to visit a pediatrician (a child doctor) and have your son examined physically and conduct a blood investigation to check on the hormone levels. I hope you find my response helpful and informative. Please feel free to write back to me for any further clarifications, I would be more than happy to help. Best wishes.

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