(Spoilers Main) Nature vs Nurture, who wins?

In this hypothetical scenario, let's say that Robert had decided to foster off Joffrey to Winterfell and became Ned's ward at a very young age (let's say he's 8-9). Let’s say after the pregnant cat situation, Robert and Jon Arryn went ‘shit, we got to kick this kid into shape....…Ned can do that.’ And let’s assume that Cersei can’t stop it. Would this have changed the story in any way? Would he have been able to temper Joffrey's worst tendencies, or would the boy still have remained the same?

One thing's for sure, NONE OF THE ADULTS in Winterfell's household would've tolerated his spoiled, psychopathic behavior. Catelyn? Nope. Maester Luwin? Also no. Ser Rodrik and Jory? HELL NO!!!!!!! And the other older boys in Winterfell (Robb, Jon and Theon) probably might've beaten the spoiled out of him in in the training yard.

But that's just me. What do y'all think?