As far as I know this episode contains the only known human telepath in Star Trek so what if instead of Dr Miranda Jones being human she could've been a member of a species that could later become the Betazoids? We don't exactly have a canon date as to when Betazed joined the Federation and it could've been quite easy to just make her one as any reference to her being human could be redone, even if she were half human, like Deanna Troi?