Flowers in the Attic

Question: It's been established that the grandfather has no knowledge of Corrine's children. When they come across a copy of his will, it states that if it was ever discovered that Corrine had children from her first marriage, she would lose everything. Since he never knew he had grandchildren why was this clause ever added?

Chosen answer: Because Connie and her husband were related (he was her uncle) and any children would be a product of incest. And if it was ever found out they had children, it would bring shame and disgrace to the family name.