The Book of Jubilees narrates the genesis of angels on the first day of Creation and the story of how a group of fallen angels mated with mortal females, giving rise to a race of giants known as the Nephilim, and then to their descendants, the Elioud.
The Ethiopian version states that the "angels" were in fact the disobedient offspring of Seth (Deqiqa Set), while the "mortal females" were daughters of Cain. This is also the view held by Clementine literature, Sextus Julius Africanus, Ephrem the Syrian, Augustine of Hippo, and John Chrysostom among many early Christian authorities.
Their hybrid children, the Nephilim in existence during the time of Noah, were wiped out by the great flood. Jubilees also states that God granted ten percent of the disembodied spirits of the Nephilim to try to lead mankind astray after the flood. According to this book, Hebrew is the language of Heaven, and was originally spoken by all creatures in the Garden, animals and man; however, the animals lost their power of speech when Adam and Eve were expelled. Following the Deluge, the earth was apportioned into three divisions for the three sons of Noah, and his sixteen grandsons. After the destruction of the Tower of Babel, their families were scattered to their respective allotments, and Hebrew was forgotten, until Abraham was taught it by the angels.