Huh, I thought the twins in her family had the power of telepathy through their birthstones. I mean, that's what the second chapter stated. I guess they just get birthstones that allow for telepathy and anyone can use them. I assumed that, since Rowoon initially never responded to her messages, he could hear her but not reply. So twins in her family don't actually have an innate bond that is invoked through the stones, they're just... born with a pair of phones. That's less interesting than I was led to believe.