People assume that if you add 2 parents in the home, these issues will automatically go away.
My mom grew up in a 2 parent household and still didn't do well in school. She said her mother (my grandmother) and her stepfather didn't pay attention to how she did in school nor did they try to help. Same thing with my grandfather, he had his own life with his new wife.
My mom was a single parent and she was very into my education even though she had to work 2-3 jobs. She put us in special programs for low income families and they had us visiting colleges, tutoring, taking community college classes while in middle school. That's why I turned out okay, it really just takes one parent paying attention, but if neither are, then the child is doomed.
That's the problem.
It doesn't matter if there are 2 parents in the home if one or neither are invested.
But, if you grow up in a household that does have 2 committed parents, it makes all the difference.
I spent 10 years of my life working as a behavioral counselor, teaching kids how to act in school, and teaching parents how to parent their children.
During that 10 years, where I worked with hundreds of children, from at least 20 different schools, elementary, middle, and high school, I NEVER saw a child with 2 dedicated parents struggle at all in school, behaviorally or intellectually.