gistfile1.py

class YourBaseModel(models.Model):

    @property
    def child(self):
        from django.core.exceptions import ObjectDoesNotExist
        for related_object in self._meta.get_all_related_objects():
            if not issubclass(related_object.model, self.__class__):
                continue
            try:
                return getattr(self, related_object.get_accessor_name())
            except ObjectDoesNotExist:
                pass