Maybe a better consequence of conceiving a child using a love potion would be little to no empathy rather than an inability to love? This, to me, makes more sense because the forced bond results in a child that has difficulty forging genuine bonds with others. It's not impossible, just difficult. And while I don't think it's fair to punish a child for the sins of the parent; it happens in a lot of mythology so*shrug*
yeah i mean you could say that would be better, but i don’t think it was necessary to begin with–why does the narrative have to be some sort of weird… “punishment”? it could’ve just as easily been tom concluding that the reason his mother died poor and alone and a death unworthy of a witch was because of love, and him choosing to see it as weakness and rejecting it as a result of that rather than a complete inability to understand it or experience it in the first place? that just seems incredibly cruel.
besides, a lack of empathy could be a completely natural characteristic and not something that had to be induced by the magical equivalent of a date rape drug but 10x worse. it is a common trait in certain personality disorders, but there’s also plenty of people who live completely normal lives and just happen to be lacking in that department.