False choice. Rand usually makes valid points in her novels but tends to wildly overstate them (perhaps in order to underscore her points). Gladwell may be somewhat reductive in his reasoning, but certainly social and environmental factors play a large role in success.
Simply put, it's both nature and nurture. It's what you do (by nature) and your circumstances (nurture) that determine success.
Simply put, it's both nature and nurture. It's what you do (by nature) and your circumstances (nurture) that determine success.