In 1964, Michael and Marlon joined the Jackson Brothers—a band formed by their father which included Jackie, Tito, and Jermaine—as backup musicians playing congas and tambourine. Michael said his father told him he had a "fat nose", and physically and emotionally abused him during rehearsals. He recalled that Joe often sat in a chair with a belt in his hand as he and his siblings rehearsed, ready to punish any mistakes. Joe acknowledged that he regularly whipped Michael. Katherine said that although whipping came to be considered abuse, it was a common way to discipline children when Michael was growing up. Jackie, Tito, Jermaine and Marlon denied that their father was abusive and said that the whippings, which were harder on Michael because he was younger, kept them disciplined and out of trouble. Jackson said his youth was lonely and isolated. In 2018, Jackson's physician Conrad Murray said that Joe had chemically castrated Michael and forced him to undergo hormone treatment as a child to stop his voice changing.