Heritage is an important part of the Wizarding World of Harry Potter. Aside from the usual themes of family and belonging, the main conflict that divides the magical community is blood status, or whether one comes from a wizarding family or a Muggle family. Pure-blood clans, like the House of Black, can trace their magical roots back for centuries and think this makes them better than Muggle-born witches and wizards. However, as Sirius Black points out, old wizarding families like his are never as pure as they purport to be.
Source：https://www.cbr.com/harry-potter-black-family-tree/
