Why can fraternal twins be different genders, but identical are always the same gender?

Sure, i wish things had turned out differently for me in vietnam. but i know things could have turned out worse, too. so ljust try to be for what i do have and do my best to be independent. i can dress myself and even tie a tie. no more playing guitar, though. if i close my eyes, i can just about hear the music. just strumming my heartstrings is what i'm doing, i suppose. how could the author best resolve this situation to create a feeling of somber regret? a. the narrator describes the difficulty in cooking for himself. b. the narrator decides to sell his guitar and take up a new instrument. c. the narrator points out that he doesn't have to wear a tie too often. d.the narrator mentions a friend who did not live through the war.