We were capable of having children, but Astoria was frail. A blood malediction, a serious one. An ancestor was cursed . . . it showed up in her. You know how
these things can resurface after generations . .
-- Draco Malfoy (CC4.3)
A Blood Malediction is a Curse carried in the blood through generations of a family, causing disease and even death (CC4.3).
References from the canon
- Astoria Greengrass, wife of Draco Malfoy, had a cursed ancestor whose Blood Malediction weakened her health and eventually led to her death (CC4.3).
From the Web
"Blood Malediction" from Harry Potter Wiki