Lynn Petra Alexander was born in Chicago, Illinois, on March 5, 1938, the eldest of four daughters.
Lynn Petra Alexander was born on March 5, 1938, in Chicago, Illinois, the first of four daughters born to Morris Alexander, a lawyer and businessman, and Leone Wise Alexander. She grew up on the city's South Side and attended Hyde Park High School, where she showed an early fascination with science and philosophy.
At just 14 years old she was accepted into an early-entrance program at the University of Chicago, an experience she later credited with shaping her intellectual independence and rigorous approach to inquiry. This precocious start set the stage for a career that would eventually revolutionize the understanding of cellular evolution.
Her upbringing in a family that valued education and debate, combined with the stimulating environment of the University of Chicago's undergraduate 'Great Books' curriculum, nurtured her willingness to challenge orthodoxy—a trait that would define her scientific career, most famously in her advocacy of the endosymbiotic theory of eukaryotic cell evolution.