I am pretty certain it is genetic, and passed on down, so by hatching you will get feisty stock.
Obviously that's why cock-fighting people were so into their breeding and genetics. I personally will not tolerate any aggression from the cockerels and they are immediately removed from any breeding programme, no matter how good
If you just want to tame him down then there are a few things, though these are best put into practice whilst the bird is young so you are regarded as the dominant flock leader
Never let him eat first, always the flock leader lets the hens eat first then himself, then any subordinate males
Never let him mate a hen whilst you are there, knock him off and chase him shouting loudly (don't know whether the last bit is strictly necessary, but I always do

)
If he shows you aggression you MUST catch him and hold him down and if necessary squeeze the back of his comb, and when you let him go make sure he runs off quick - if not repeat the process.
Then when he is calm speak to him softly and give him some tidbits. Penning in a large cage at eyelevel for a while seems to make them very tame quite quickly

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All the best with him - whatever you decide
Sue