Yes, CAINS is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, I 1, N 1, S 1.

Is it a valid word?

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

(Old Testament) Cain and Abel were the first children of Adam and Eve born after the Fall of Man; Cain killed Abel out of jealousy and was exiled by God