We always fall back on the same answers...and they may be true sometimes...sometimes not. More often than not? I dunno.
My father grew up in a family where his father, (a professional boxer, doorman, ne'er-do-well), left them during the Depression. He and his two brothers and sister were put into various foster homes as my grandmother found herself incapable of taking care of them all for one reason or another.
My father got into Stuyvesant H.S. which was a school you had to compete to get into in NYC. He would have gone on to college but he got out of high school, went to work, reunited his younger sister, and two younger brothers with his mother and became their sole income during the Korean war, until his brothers went into the service. All this while getting married at 20 and raising a family of his own as well.
They had no history of higher education. I was the first one to go to college in my family, though my father would have thrived. My mother, a voracious reader, might have as well but for being content to raise a family.
My friend, didn't need a family to support him in college as he got a full ride to Brown. And deserved it, for academics alone.
The generalizations may be more true than not, but they are clearly not the entire picture. Anyway, it is what it is. We just don't always understand what it is.
Though I don't dispute that having the support of a family, (that cares about education), is clearly a plus.