If It is true that masturbation/sex caused baldness; then almost all p**rn stars would be bald or have hair loss, not the case however.
Second if masturbation, causes hair loss by the overstimulation of the brain during the imagination of the sex act, then why arent most scholar/scientists who use their brain most heavily have more hair loss?? Look at einstein. He should be bald then, nobody used as much of their brain as he did. He had a full head of hair.
The best indicator for baldness, is to have a bald father or grandfather.
That is how you really can tell. Its obviously inherited. Just like a father who is 6'4 isnt likely to have a son 5'4, a bald father is more likely to have a bald son. I've seen this hundreds of times in families, I think everyone has.
What everyone is referring too, is castration. Yeah if you get castrated before puberty you wont lose your hair. No dht. This is a fact, there were castrati, who were castrated for their singing voice, for opera, a few hundred years ago. They never lost their hair. Otherwise you got balls and they function right, and you have the hereditary gene for dht then you will have hair loss. It doesnt matter how much you masturbate or have sex. You would have to cut them off before puberty to stop the testosterone and the dht.