The arrival of the second child in the first human family introduces the marvel of human diversity and the division of labor. Because his birth is described as an immediate continuation of the same pregnancy, most commentators agree that Cain and Abel were born as twins [רד״ק, מזרחי, הכתב והקבלה]. Linguistic cues hint that twin sisters were born alongside them, providing the means for humanity to multiply [אור החיים, תורה תמימה, ביאור יש״ר]. The emphasis on their status as brothers carried an expectation that the younger sibling would assist the older in his work or remain under his authority [אדרת אליהו, קאסוטו]. At the same time, it serves as a tragic foreshadowing, as Abel would act with true brotherly devotion, while Cain would ultimately alienate himself [אור החיים].
Unlike Cain, Abel was given a name without an explicit explanation. The primary approach among commentators is that his name symbolizes transience, emptiness, and a rapid end. It served as an unconscious prophecy from his mother that his life would be cut short abruptly [שד״ל, רד״ק, קאסוטו]. She may have avoided explaining the name to hide the bitter realization that every human acquisition ultimately ends in nothingness [ברכת אשר]. Alternatively, the name might reflect a deep sense of spirituality [ביאור שטיינזלץ], or it could simply be an ancient term meaning a son or child [אם למקרא].
As the brothers matured, they divided the basic economic sectors between them. Because humanity was forbidden to eat meat until the Flood, shepherding was strictly for producing milk, cheese, and wool [רד״ק, מזרחי, שפתי חכמים]. Abel's choice of profession may have stemmed from a desire to distance himself from the soil that God had recently cursed [רש״י, מזרחי]. Others view shepherding as a thoughtful pursuit [ספורנו] that allowed for quiet isolation in nature, freedom from material burdens, and spiritual elevation, setting a precedent for the future fathers of the nation [הכתב והקבלה]. The gentle care required to tend to animals also highlighted his altruistic character [פרדס יוסף]. A dissenting view, however, argues that seeking out milk and wool was a pursuit of unnecessary luxury rather than basic survival [העמק דבר].
As the firstborn, Cain took on the vital task of working the land to secure humanity's essential food supply [העמק דבר, גור אריה]. In the ancient world, farming was often viewed as a stable, superior profession desired by God, while shepherding was considered a lesser role [מלבי״ם]. Yet, many commentators criticize this choice, arguing that Cain degraded his soul with purely material pursuits and was drawn to the cursed earth due to a deep spiritual flaw [הכתב והקבלה, צרור המור, גור אריה].
The subtle phrasing used to describe their occupations highlights a profound contrast between the brothers, demonstrating how a single origin can produce completely opposite natures, one righteous and one wicked [רבנו בחיי]. This distinction suggests that Cain either deliberately sought a different path to distance himself from his sibling [קונטרס חיבה יתירה], or that he had already established himself in his earthly labor long before Abel chose his own profession [גור אריה, הטור הארוך].