Marcus was born on October 8, 1962, in Pittsburgh, Pennsylvania, and grew up in Sonoma, California. He was the valedictorian of Sonoma Valley High School 's class of 1980, and attended Stanford University, graduating with a Bachelor of Science degree in physics. He later received Master of Arts and Doctor of Philosophy degrees in physics from Harvard University. His doctoral thesis, published in 1990, is entitled Dynamics of Analog Neural Networks.