Adding on to what others are saying, the raw data is a measurement of our world, and the way we have constructed and formed our world is inherently biased. People are congregated into clusters physically, economically, and socially for all manner of reasons, many of which are unfit criteria for selection. Even after unjust actions are halted, they leave echoes in how the lives of those people and their children are affected: where they grew up, where and how much property they may own, where they went to school, and so on. Those unfit criteria are leaked through anything that gives a proxy measure of those clusters, sometimes in surprising and unintuitive ways that cannot necessarily be scrubbed out or hidden.