What is did cain have a twin sister?

There is no mention of Cain having a twin sister in the Bible. The only mention of his siblings is his brother Abel. However, there are some extra-biblical texts, such as the Book of Jubilees and the Book of Adam and Eve, that mention Cain having a twin sister named Awan or Avan. These texts are not considered part of the canonical Bible and are not universally accepted by all Christians. Therefore, the existence of Cain's twin sister is a matter of interpretation and belief.