Edgar and Sabin are twins, yes. Lenna and Faris aren't twins, it's shown in the game in a flashback how Faris' parents were away and she had to take care of her little sister, Lenna. I'm not sure if you can consider the Onion Kids in FF3j NES quadruplets (sp). Palom and Poroms are twins, though of different genders. I'm not totally sure about (FFIV Spoiler)Cecil and Golbez. I don't think Zorn and Thorn are twins because Kuja says, "Don't worry, I hear these twins put on quite a good show. Of course, they're really not twins at all..."