The man Adam knew his wife Eve intimately. She became pregnant and gave birth to Cain, and said, "I have given life to a man with the LORD's help."
References for Genesis 4:1
She gave birth a second time to Cain's brother Abel. Abel cared for the flocks, and Cain farmed the fertile land.
Some time later, Cain presented an offering to the LORD from the land's crops
while Abel presented his flock's oldest offspring with their fat. The LORD looked favorably on Abel and his sacrifice
but didn't look favorably on Cain and his sacrifice. Cain became very angry and looked resentful.
The LORD said to Cain, "Why are you angry, and why do you look so resentful?