1530s, from Middle French hérédité (12c.), from Latin hereditatem (nominative hereditas) "heirship, inheritance, condition of being an heir," from heres (genitive heredis) "heir, heiress," from PIE root *ghe- "to be empty, left behind" (source also of Greek khera "widow"). Legal sense of "inheritable quality or character" first recorded 1784; the modern biological sense seems to be found first in 1863, introduced by Herbert Spencer.