"After graduating from the Bronx High School of Science in 1959 at 16 as class valedictorian, he studied mathematics at Harvard. A clean-cut supporter of Adlai E. Stevenson..."

"... he fell in love with a woman whose parents had been communists. She opened his eyes to folk music and to an outlaw culture that fascinated him, and he became involved with a peace group called Tocsin. Before he graduated in 1963, he met Tom Hayden and other leaders of what was then a tiny organization, Students for a Democratic Society. 'I wanted to be like them,' [Todd] Gitlin wrote in 'The Sixties.' 'These exalted, clear, somehow devout souls so loved the world.'"

From "Todd Gitlin, a Voice and Critic of the New Left, Dies at 79/He earned his stripes in the antiwar movement of the 1960s. In his later years, he was often critical of his erstwhile kindred spirits" (NYT).

Note the centrality of love. You have someone super-smart — valedictorian at Bronx Science at 16 — and studying math at Harvard, supporting the Democratic Party candidate, and he falls in love. He joins up with radicals because, in them, he perceives love. 

Or so his story is told in the NYT obituary.

I see I have a tag for Todd Gitlin, and I'm surprised to see that I've used it 9 times in the 18-year history of this blog. In 2015, I quoted something he'd written in 2003:

"My generation of the New Left — a generation that grew as the war went on — relinquished any title to patriotism without much sense of loss. All that was left to the Left was to unearth righteous traditions and cultivate them in universities. The much-mocked political correctness of the next academic generations was a consolation prize. We lost — we squandered the politics — but won the textbooks."