Wow, I'm amazed you got that from any sort of "contemporary" Sociology class: the acknowledgment that "Dads are essential" [for proper upbringing of children.]
Boy are you showing how young you are.
I guess you never saw the sitcom "Murphy Brown." It was just a series that reflected the "down with men" and "down with dads" era.
The sociology classes gave credence to the eon-long knowledge that the modern feminists were disparaging. That probably means nothing to you though. So be it.
Also, dads or moms are sometimes dead, traveling, etc., and aren't always around. WHY mom or dad are gone is as important as their being gone.
Duty is a good reason for being away; desertion just makes children know that they are abandoned and unwanted.