A decade before we'd seen them, it has been hinted that Scott's home life is not that great. In "Butters' Bottom Bitch", after getting kissed by Sally Darson, he says "It's almost like having someone care about you."
In "Skank Hunt", when ranting to Mr. Mackey about quitting Twitter, he says that his dad told him he's better off without it.
In "The Fractured but Whole", it was implied that his mom is an alcoholic, as he says that gin and tonic always knock her out.
When we finally get to see them in "Basic Cable", I was right about his dad Clark, because it's not like all the dads of South Park are any different these days. Being a massive prick to him, even mocking his diabetes behind his back.
As for Ellen, at least she does care about Scott, considering he asks him about his blood sugar, compliments on it being at a normal level, and congratulates him on him finding a friend in Sophie Gray. Going back to TFBW: now that I think about it, Ellen might've tried a gin and tonic one time, and Scott exaggerated her response to it.
Going back to Clark: he belittles his own son out on insecurity. I thought about this last night, and both he and Ellen are out of shape, so Clark makes himself feel better by using his son as a lightning rod. I don’t know what T&M have against dads (or parents in general), but I’m getting tired of it.
Also, it's good that even Clark has standards, as shown in the "Vaccination Special", where he think Garrison was a shitty teacher/president.