Let's be honest, the reason so many people are opposed to this view is because it has been wrongfully used in the past to justify very real oppression and inequality of opportunity. At the very least, it is a very dangerous mindset historically, and even now it's not very well understood.
For example, in the study you mentioned around Korean twins, one was raised in a fairly standard Korean household while the other was tossed around the foster care system and had multitudes of setbacks given to them. And yet people will still use it as evidence that these differences are inherent and unchangeable. Do you not see how this reasoning can lead us to ignore our own blindspots and biases?