Both Godfrey and Dunsey Cass turned out to be less than any parent would have wanted their children to be. Dunsey, the youngest, was described as a "spiteful jeering fellow", who was a drunk, a gambler, a liar, and a double dealer. He manipulated his older brother, Godfrey, and seemed to always get away with most.
Godfrey, on the other hand, was not as able as his father in the area of business, followed the ways of his brothers, got in a bad marriage, and seemed to have no clue on what to do with his life other than to love Nancy Lammeter in secret.
The situation with their life was that the mistress of Red House, the mother of Dunsey and Godfrey was dead. She died apparently when the boys were at a young age and their father, Squire, had to take care of them from early on.
We can easily argue that Squire's behavior towards life and people in general were neither emotional, nor sentimental, nor maternal, nor paternal. He was a business man and a hard working one at that. Perhaps he was too harsh on his children and they cowed down. Maybe he was too lenient and they got used to having it all. We are not specifically told in the story how their upbringing was, but the women in the story always had a very important role in the upbringing of children.
Therefore, Elliot may have wanted to explain to us that, had Mrs. Cass been alive and around her children, they would have had a balanced family life and may have been able to find themselves before acting in dangerous and childish ways until their adulthood.