If gameness is determined genetically, (how) can it be ruined?

Case for example, let's say you would roll a dog who isn't fully matured/not ready. He scratches, but doesn't really start fighting/biting. Keeps crying when the other dog bites him. You still let it go for 4/5 minuts in the hope he would open up. When you want to let him go the 3th time he stays between your legs.

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If he or she IS fully matured, stopped the crying and he really starts biting. Would he more likely to stop because he was wasted earlier or was he a cur from the get go?
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