All happy families are alike; every unhappy family is unhappy in its own way. What's true for depressing Russian novels is true for depressing Shakespeare plays, especially ones that portray the city of Rome as a large, dysfunctional "family" unit. In Coriolanus, the upper class patricians are like a bunch of lousy "parents" and the lower class plebeians come off like a crew of unruly "children." By dramatizing Rome's social and political problems, the play suggests that that those who hold all the power in a complex society have an obligation to care for the common man, just like parents have an obligation to care for their kids. Of course, maybe the plebs are better off being neglected. Shakespeare shows us one version of familial love: Coriolanus' wacky slash seriously dysfunctional mom, who fails to nurture her son and instead raises him to be a killing machine so she can bask in the glory of his military and political achievements. If that's the alternative, maybe being a latch key kid isn't so bad after all.
There's no such thing as a good mother in Coriolanus.
Coriolanus' relationship with his family makes him vulnerable and human. When he's not around them, he's just a heartless war machine.