jail ministry

I really don’t understand why Narcissa didn’t inherit the Black estate when everyone else in the family is disowned, dead, or in jail?

Ministry: you can’t have the house it is Sirius Black’s
Narcissa: he was disowned here is his mother’s paperwork to prove it
Ministry: well it’s Regulus Black’s then.
Narcissa: he is dead
Ministry: okay welll you’re a GIRL you can’t inherit anything hahaha
Lucius: what did you say.
Ministry: I said good morning Mr. Malfoy here is the title to grimmauld place.