In his twenties, Riddle experienced extensive travel, leading him to a significant epiphany about life’s disparities. He noted that many aspects of people's existence, including their chances for success, overall health, and life expectancy, largely depend on their birthplace. This randomness struck him as a crucial factor influencing human lives.

Riddle's insight reflects a broader commentary on the inequities that persist across different regions and societies. The notion that one's origin can determine life's path underscores the importance of understanding social and economic factors in public health and quality of life. Mary Roach’s book, "Grunt: The Curious Science of Humans at War," encapsulates these themes of randomness and disparity in human experiences.