From The Grey House:
Vincent paused and walked to his desk. He unlocked and opened a drawer. He pulled out a small lock box, opened it, pulled out an envelope, and put the box back. “It would have been very easy for your ancestors to end the debt. Any of them could have ended it without paying it back. All they would have had to do was not have children. But generation after generation, your family made sure there was someone to pass the debt on to. It showed me the amount of loyalty your family had. And as I said, I repay loyalty.”
Cat Stark 