Some born and some made. For example, Trinidad was a skinny fighter who had a high percentage of KO victories. Why? Because he wrapped his hands illegally to make them hit harder than usual. Margaricheato was another example. He put bricks into his gloves to knock his opponents out. Tyson, McCanland, and Jackson were born to be punchers.
If you don't have proper technique then you won't punch hard. I couldn't punch at all until I improved my technique. Lifting weights helped big time as well.
Proper technique's always a plus, R, but no substitute for heavy hands. Luis Firpo could drive ya into the ground like a tent peg with wild swings.
being a puncher is a mentality, thus punchers are born . Guys like Tyson, Pacquiao, (etc) put everything in their punches. The have that punchers mentality. A lot of physical talent helps too.
I have trained with steward an he told me when tommy hearns was an amantuer he only stopped something like 8 opponents in over 100 fights. When he turned pro emanuel said he started to get hearns to learn to punch throw his target an trained him to be more ferocious in his punching heanrs then started knocking people out for fun. I think being a puncher is based on of course having the physical attributes like power speed technique punching through your target but a big part of all that is being ferocious. Throwing a punch like your exploding through your target. You have to throw your punch with a great amount of intensity whilst being relaxed.