I think the more common example is disowning a parent rather than a grandparent. Whether the disowned parent is parasitic or lacks volition, well, that’s a matter of opinion.
The human embryo certainly has a number of parasitic characteristics. Obviously it siphons nutrients from the mother’s bloodstream; it has prolonged direct contact with the mother; but also, apparently “[t]he placenta acts like a parasite to avoid attack by a mother’s immune system”.
Obviously there are major differences, how many parasites are found solely among hosts of their own species? The closest I can think of is the practice of say, ducks laying eggs in other ducks’ nests (intraspecific parasitism). Parasitic castration (diverting energy/resources from reproduction to the parasite) is a major form of parasitic behavior, but actual reproduction is not usually considered a form of parasitic castration.