In Outliers: The Story of Success, Malcolm Gladwell considers the circumstances that lead to success. The first half of the book looks closely at how opportunities matter more in the lives of successful people than hard work or raw talent. The second half of the book focuses on cultural legacies: behavioral tendencies rooted in their ancestral past.

Part One examines the role of opportunity in the lives of extremely successful people. Gladwell’s first example is the Canadian Hockey League, the world’s most competitive youth hockey league. Since the cutoff date for the Canadian leagues that serve the youngest players is January 1, those born in the first part of the calendar year are much larger and more coordinated than their peers. The larger and more coordinated kids are given more playing time and better coaching, and thus become better players by the time they reach the top league. An overwhelming majority of Canadian professional hockey players have birthdays in January, February or March.