Genesis 4 :6,7 (KJV)
6 And the Lord said unto Cain, Why art thou wroth? and why is thy countenance fallen?
7 If thou doest well, shalt thou not be accepted? and if thou doest...
Mormonism: The Mark Of Cain Equals Black Skin
The curse of Cain, being black skin, is a Mormon teaching only and not taught in Christianity, nor being in the Bible.