>>151152095
>instead of having a normal childhood like Ennis said he had
It wasn't written by Ennis but Punisher MAX as a child was already ready and willing to kill a young guy who was essentially raping women around the neighborhood. But before he can do it he witnesses the guy get set on fire by some other guy who was a Marine.

So even before his time in Vietnam or the death of his wife/children he already had that inner spark of him as a kid of wanting to be a predator that went around killing the bad guys. And it's probably not a coincidence he specifically became a Marine after being influenced by that Marine he saw kill somebody else.