Complex sentence: Around 1955, his sister married Joe Barbera, of Hanna/Barbera, who became extremely successful in the cartoon industry; as a result of the marriage, the family moved to California where Brian attended Hollywood High.
Split into simpler sentences: Around 1955, his sister married Joe Barbera, of Hanna/Barbera, who became extremely successful in the cartoon industry. As a result of the marriage, the family moved to California where Brian attended Hollywood High.