 Barrowman graduated from high school in 1985 , and became a naturalised citizen of the United States ( although he maintains dual citizenship of both the United Kingdom and the US ) . After he graduated from high school , he moved to San Diego , to study performing arts at the United States International University ( <unk> ) . As part of an exchange programme , he returned to his native Britain in 1989 , to study Shakespeare for six months . 
