recursive_fk.py

>>> class Person(models.Model):
...  name = models.CharField(max_length=20)
...  parent = models.ForeignKey('self', null=True)
>>>
>>> p1 = Person.objects.create(name="Grandpa")
>>> p2 = Person.objects.create(name="Dad", parent=p1)
>>> p3 = Person.objects.create(name="Child", parent=p2)
>>> who_has_a_grandpa = Person.objects.filter(parent__parent__name="Grandpa")
>>> who_has_a_grandpa.name
u'Child'