He glances over the instruments, some of which are familiar, some of which are not. "My father played the harp," which he's sharing mostly just to provide the information. Even without the memories from the alternate version of himself he would know this about his father. Long before he knew the truth of his parentage he had known the story of how Lyanna and Rhaegar met. He just hadn't known the whole story. They'd fallen in love because of that harp. He exists because of that harp.