In some circles, Sarah Grace Morris is a celebrity, especially in circles where her brother, the rapper known as MattyB, is a star. Sarah Grace has her own YouTube channel with, at last count, 217,015 ...

“OMG, there he is. We love you, Matty!” screamed hordes of adolescent girls waiting in line to meet their favorite music artist — and, likely, crush — the up-and-coming rap singer Matthew Morris, ...