Bad Fathers

Why are there so many bad fathers in this book who can't take good care of their children but want to keep them nevertheless? I think an ideal caretaker for Linton and Hareton would have been Nelly. She's capable, amiable and obviously a good housekeeper (since it seems like she's been working at the two manors for ages). But NO! Hindley and Heathcliff must INSIST upon taking care of their own sons and then succeed wonderfully in paying no attention to them. I have a theory that they make sure the children are under their custody and then they can make sure the boys will have a terrible life of neglect and sadness. We know from the book that both Hareton and Linton were not really wanted by their fathers but they still had to live with them and endure their hatred and cruelty. Hareton, who was a direct descendent of the man who built Wuthering Heights should have been a gentleman of sophisticated dispositon and high cultivation in academics and social aspects of life but instead, he was uneducated and unruly because of the way he was raised.