Genesis 4:2

His brother Abel. The absence of the usual expression “and she conceived,” and the use of the peculiar phraseology “she again bare,” literally, “she continued to give birth,” have suggested to some commentators that Abel was Cain’s twin brother. This may be true but is not necessarily implied by the text. Abel’s name means “vanity” or “nothingness.” It reflects the fact that either a mother’s hopes had already met with disappointment in her elder son or that Abel personified for her the miseries of human life. In this chapter Abel is seven times called Cain’s brother, seeming to emphasize the heinousness of Cain’s sin.

A keeper of sheep. There is no reason for finding in the professions chosen by the two men an intimation of difference in moral character, although these choices were probably determined by their talents and tastes.