Manasseh was, according to the Book of Genesis, the first son of Joseph and Asenath.
Asenath was an Egyptian woman whom the Pharaoh gave to Joseph as wife, and the daughter of Potipherah, a priest of On. Manasseh was born in Egypt before the arrival of the children of Israel from Canaan.
According to the Biblical account, the name Manasseh, the name Joseph gives one of his sons, means "God has made me forget".
Jacob (Joseph's father) adopted Joseph's two sons, Manasseh and Ephraim, so the boys might share in Jacob's inheritance equally with Jacob's own sons. Manasseh is counted as the father of the Israelite Tribe of Manasseh, one of the Twelve Tribes of Israel.