Yes, GENESIS is a Scrabble word!

Letter values in Scrabble US: G 2, E 1, N 1, E 1, S 1, I 1, S 1.

Is it a valid word?

GENESIS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a coming into being
the first book of the Old Testament: tells of Creation; Adam and Eve; the Fall of Man; Cain and Abel; Noah and the flood; God's covenant with Abraham; Abraham and Isaac; Jacob and Esau; Joseph and his brothers

Also: book of genesis.