The narrator of The Round House is called Joe. What is his legal name? Why does he prefer to be called Joe?

In chapter 4, Joe states that he is named after his father, Antone Bazil Coutts, but hates the name so much that he says that "I'd fight anyone that put a junior in back of my name." He began calling himself Joe at the age of six, but he states that even that name is not ideal. He originally wanted a named that distinguished him from the other males in his family; however, at the age of 8, he found out that Joseph was the name of his grandfather.
Joe calls the character traits of the men in his family, which he states include "responsible" and "upright", tedious. In comparison, he admits there is something strange about him: "I was the sort of kid who spent a Sunday afternoon prying little trees out the foundation of his parents' house." He has no doubt he is different but says he has yet to grasp how.