This is begging the question. While, yes, there are developmental and cognitive disabilities, both inborn and acquired, that can reduce cognitive function, I h

This is begging the question. While, yes, there are developmental and cognitive disabilities, both inborn and acquired, that can reduce cognitive function, I have yet to see evidence that among people without any specific diagnosable disability, variations in "intelligence" cannot be explained (at least 80-95%) by, essentially, variations in upbringing. From my personal observation (so no, not a scientific sample), people raised in a household where education is highly valued, by parents who genuinely care about them and are (able to be) engaged in their development and schooling tend to exhibit more of the traits of intelligence than people who are raised in households where education is derided as something for sissies or liberals, or where the parents have to work too many jobs just to keep food on the table to be able to be engaged in their children's lives. Now, to be clear, I'm not saying "everyone has exactly the same potential in all areas." There are enough natural physiological and neurological variations to ensure that, for instance, I'm better at foreign languages and programming, while my wife is better at research, art, and people management. But I know enough about the psychology of motivation and mindset (eg, entity vs growth mindset) to know that the things we believe about ourselves and the world greatly color what we are able to do and become—so if we are able to change our mindset from, for instance, "I'm just bad at math" to "I was never taught math in a way that engaged me; I can get better if I want to", then we can achieve things that previously seemed impossible. That's triply true for getting ourselves out of situations (like crushing poverty) that restrict our mindset and our abilities.