Balbira & Kalmana were the respective wives and twin sisters of Abel & Cain. According to the Bible, Adam and Eve had three sons: Cain, Abel, Seth and additional sons and daughters. Two of the daughters names appear in Seder HaDorot (The Order of the Generations): Kalmana, Balbira. In an effort to explain where Cain & Abel acquired wives, some traditional sources write that each child of Adam & Eve was born with a twin who became their mate. According to the Seder HaDorot, the wife and twin sister of Cain was named Kalmana and the wife and twin of Abel was Balbira.