Why is it that the penis length of a teen is always bigger then that in his twenties?I wondered, but its true.

Question

I checked that when I was 18 my penis size was the largest, with the passage of these 3 years it might have reduced by couple of millimeters, now that's really starnge :-)

Answer 1

No, your penis does not "shrink" unless you have a medical condition (leading to a curvature) or are receiving cancer treatments. It will also measure smaller after swimming.

A male will grow until he is 21 years old. As for the penis, the size is determined by genetics. Medicine will tell you that you need to wait until 2 years after you stop growing to know what size your penis will be as an adult. So, you probably won't know that information until you are 23. For more info:
http://menshealth.about.com/cs/penishealth/f/penis_growth.htm