Meghan Trainor's sons, Riley and Barry, are already proving to be the best big brothers to their new little sister. "They are over the moon. Riley takes his 'big brother' role very seriously, and Barry is just so gentle and curious with her," Trainor, 32, told People on Tuesday, January 20, after announcing the arrival of daughter Mikey Moon via surrogate. "Watching them bond with their sister has been one of the sweetest parts of this whole experience.