Complex sentence: Sheldon has a twin sister, Missy, a tall, attractive brunette and a yet-unseen older brother, George Jr. Both Missy and George Jr. beat Sheldon up during their childhoods, and their mother describes them to be "dumb as soup".
Split into simpler sentences: Sheldon has a twin sister, Missy, a tall, attractive brunette. Sheldon also has a yet-unseen older brother, George Jr. Both Missy and George Jr. beat Sheldon up during their childhoods, and their mother describes them to be "dumb as soup".