From Gineipaedia, the Legend of Galactic Heroes wiki
Grandpa dusty had at least one daughter, Mrs Attenborough, whom he refused to let marry anyone who was not a soldier like himself. When she eventually fell in love with a journalist, Mr Attenborough, Grandpa Dusty was incensed. Initially opposed to the union, he eventually allowed it on the condition that his grandson were to be a soldier. Unfortunately, his daughters first children were all daughters, and Grandpa Dusty died in a battle against the Empire a few months before the birth of his first grandson.
On Dusty Attenborough's first day in the FPA Officer Academy, Mr Attenborough gave his son a rusted key, which Grandpa Dusty, in turn, had given him on the day of his daughter's wedding. The rusted key was a good luck charm, which had allegedly once saved Grandpa Dusty's life from a stray bullet.