Pansy's father did. Milli's parents don't, nor do Daphne's. Moran's father does. It's more fathers than mothers but Hydra isn't the only one whose parents both have a Dark Mark.

A lot of the people who have them are quite dangerous. I mean no one in their right mind gets in Bellatrix Lestrange's way. But Hydra's father doesn't seem too bad. And Regulus Black isn't -- well at least he isn't like Bellatrix.