My old college roommate is a high school teacher with 15+ years in the classroom. He says that the single most important factor in determining a student's success is parental involvement.
According to him, it's more predictive than race, gender, income, geography. Children whose parents are involved in the child's education (attending conferences with teachers, emailing or phoning back and forth, serving as chaparones on field trips, tracking homework completion, and so forth) will do better in school than children whose parents are not involved.
He tries to involve parents. He sends the class schedule to parents, including what assignments are due and when, when exams are scheduled and what material will be covered, and invites them to phone/email him with any questions or concerns, schedules parent conferences at the parents' convenience, and so forth. He says the response rate is extremely low...and that's for all races.
I'm sure studies of white children would show the same results (weighted for parental involvement) as his study of black children.
My wife is a grade school teacher, and would largely back up your roommate's theory. She finds, though, that there are some parents who are heavily involved, but usually in making excuses for their child. Every year there are 1 or 2 like that - I usually start hearing the names early in the year, and know I will hear them repetitively the rest of the year. And those kids usually don't do well - the next year's teachers find them just as bad as my wife does.
On the other hand, the majority of parents who are involved with their child's schoolwork do quite well.
Drew Garrett