When an angel Falls, she defects to the human race, and takes on everything that comes with that choice. All of the joy and heartbreak of humanity are hers, and that includes family.
Heirs to Hell discusses the children of the Unchained, and presents system and setting information for including these demon-blooded in your chronicles. Some demon-blooded are completely unaware of their heritage, and some are very much inheritors of their demonic parents' power. But the God-Machine has plans for all of them.
A cool idea that can leads to a lot of very interesting character creation, the idea of giving players to ability to create a child for their demon character has a lot of possibilities. In fact it can lead to a lot of interesting ideas for a game sessions that can focus on a family.