Domino

Without getting into this fully, it provides an excuse to point out that even relatively small amounts of racial bias sprinkled through the system can ultimately lead to rather large difference in outcomes, due to perfectly rational responses by those affected by racism. The basic story is that if you have to work 10% harder to do as well, you're probably going to work less hard. In economist speak, if the marginal benefit is less than the marginal effort you aren't going to bother. The stories of those exceptional individuals who rise above the system are heartwarming, but as a society we compare those individuals with the people who were born on third and narrowly manage to stay there even as they inexplicably and repeatedly try to steal second. When kids born to insane privilege barely manage to navigate their way through their teen and college years, it's absurd to expect a significant number of kids facing racism and other barriers to all hit homers their first time on the field.