The Bible only mentions one, Enoch, whom is probably the firstborn because he was the only one mentioned. Most likely Cain had many other children because most people mentioned in the Bible back then...
Three........ Shakespeare was married to a woman named Anne Hathaway. In May, 1583 she gave birth to a daughter, Susannah.In January/February 1585 Anne gave birth to twins, Hamnet (a boy) and Judith.