I'm trying to figure out why you've posted this, without context nonetheless. Where's the data on the income makeup? A sole earner and two earners will impact a child's development very differently due to factors such as "kids who are read to perform better". Other factors would include things like mortgage discrimination (are the kids growing up somewhere healthy or are they redlined). Is it actually safe for them to be outside and active? Do they face stop and frisk or community fear-mongering and all the associated anxiety and depressive influence that has on teen development? The graph you've posted is a cherry-picked data point with no meaningful discussion.
There's a lot of crazy excuses a person can come up with for why the poorest white children perform on the same level as the richest black children. What makes this data "cherry-picked"?