There are to many factors that can determine this.. Everyone is differnt but the idea of not wanting to get KTFO is the same. You have to find what works for you. I think development at a early age helps with defining your chin. Im not saying beat the shit out of ur kid and he will have a iron chin. But I am saying the more he is exposed to ruff sports and so on will help in the long run.. Also natural pain tolerance helps to..
Like with me Ive broken 17 bones and had reconstructive knee surgery and so on.. I have a high tolerance to pain. When I was like 7 I snapped my chin into and it stabbed through my leg. More then anything it scared me being a kid but once I was in my moms car and she told me to shut up I jus looked at it and poked at it.. lol. WHen I get punched I dont really feel it in a negative way.. Im not saying I can't get knocked out cause thats not the truth I fell 6 feet once onto my head and was knocked out for like 30 seconds. . Some people can take pain better then others from personal experience ,natural ability and conditoning of there body. All in all anyone can get kocked out its jus the ability to be able to mentally muscle through that. Which in all isnt really a good thing at all.. You need a natural on and off switch so in certain sito's you do not recieve brain damage.