There's a nice essay on the concept of a "blank slate" in Quillette.
The basic idea of a blank slate is that all humans are equal in capacity. It's a foolish notion, but it's a nice one, and it's usually a notion associated with the left: The left recognizes that the world is not a place of equal opportunity, that people are saddled with all sorts of disadvantages by nurture rather than nature, and that all too often people try to wrongly shift the blame from the cruelty of man (nurture) to the cruelty of unequal genetic endowment (nature). Some even go farther and (wrongly!) ascribe the disadvantages of entire groups not to the cruelty of man (nurture) but rather genes (nature). Consequently, people on the left tend to be suspicious of genetic explanations of human behavior. To the extent that this suspicion is merely skepticism of hypotheses that are difficult to prove and often wielded to evil ends, it is an intellectually healthy suspicion. To the extent that it is a rejection of neurobiological inquiries into human behavior it is an unhealthy suspicion.
The author in Quillette points out that the right has its own version of a blank slate: They argue that not only are people born equal in natural endowment, they remain equal in practical capacities even in the face of unequal nurturing, and hence unequal outcomes are primarily the consequence of bad choices, or moral failings. It is as absurd as rejecting the idea that individuals' brains differ in part because of genetic variability among humans. If the left is insisting that the slate was blank at birth, the right is insisting that the slate has NOT been vandalized even after years or decades of unequal conditions in a cruel world, or that the marks are at least easily erased.
Of course, the left has its own moral analysis as well: While recognizing that it is absurd to expect the disadvantaged to simply shrug it all off and succeed equally, some do insist that college professors would obtain equal outcomes if we merely gave enough chances, and were enlightened enough in our evaluations. If we just followed "best practices" then we would see gaps shrink substantially, and the persistence of gaps thus follows from our choice to abstain from "best practices." It shifts the moral responsibility from the vandal who made the mark to the professor who was unable to erase it.
Like all seductive lies, it's partly true: Some people will, if given a chance and some support, defy the odds and rise to the occasion. To structure educational programs as Darwinian competitions with one chance and no more is both foolish and unethical. (I will note that my grading formula rewards improvement and provides some forgiveness for initial failures.) But it is important to recognize that working to remedy inequity in this way is costly and risky. It won't always work, and it will cost more than simply giving one chance and moving on. If you nonetheless value opportunity then you will accept costs and risks. If you don't actually value opportunity then you will deny that it has a cost (because that which is without value is without cost) and insist that the only problem is a failure to identify the "right" criteria, the "right" measures.
I remark on this because, as I have noted before, our theories of success and failure can be double-edged swords. A theory that success that success is rooted in "grit" or "growth mindset" is the key to success (rather than evil standardized tests) can be shiny and progressive if it is used to undermine evil standardized tests, but it can also be turned around and used to blame the poor and disadvantaged for lacking the moral virtues of grit and growth mindset. A moral theory that says we are all equal in capacity can be used to blame a cruel world for failure, but it can also be used to blame failure on choices by people of presumably equal capacity. The fact that the left and right go in such different directions from ostensibly similar assumptions means that there are additional embedded assumptions that people aren't always articulating openly.
For me, I will be disappointingly wishy-washy and say that EVERYTHING matters for success and failure. Some kids really ARE born smarter than others. Sorry, but it's true. On the other hand, unequal conditions in life will ALSO leave their marks. Some of those marks CAN be erased. Others are much harder to erase. Some people will surprise you and outperform expectations. Some won't. It's worth it to give people a chance. It's ill-advised to keep pouring in resources as the returns diminish. Some people really do fall on bad choices or rise on good choices. Some people are stuck. Abandoning personal responsibility in your moral calculus is ill-advised, but so is treating personal responsibility as the only variable. It's complicated and we have to muddle through.
I wish I had some sort of magical solution, but I don't.