Adam and Eve had many sons and daughters, Genesis 5:4. But Cain and Abel seem to have been the two eldest. Cain signifies possession; for Eve when she bare him said with joy and thankfulness, and great expectation, I have gotten a man from the Lord.
Related Commentaries of Genesis 4:1
Genesis 4:1
1 And Adam knew Eve his wife; and she conceived, and bare Cain,a and said, I have gotten a man from the LORD.