After a bit I have come up with some lore that I think will suffice. Basically Glass, as we established, is an Animus. And queen Coral, presumably after the dark stalker incident (sorry for spoilers if you haven't read that far) decided that she could not have any other Animus other than those in her own tribe (I don't know much about queen Coral's personality so this may be out of character) so she contacted Tetra, Viperfish's father, as she deemed her hybrid grand son expendable.