Doug Hanahan was born in Seattle, Washington. His father was a biochemist and Hanahan was exposed to the world of the "scientist" early on. He did not have any special interest in science as a child, but he did go to Massachusetts Institute of Technology and graduated with a degree in physics in 1976.

It was at M.I.T. that he first developed an interest in biology. He took a class taught by Salvatore Luria, which opened his eyes to the power of the genome. Until this class, Hanahan thought that biology was boring and involved memorizing the names of animals. He entered graduate school in the (then) Biochemistry and Molecular Biology department at Harvard University to join the biology revolution.

Although he was a Harvard graduate student, from 1979 to 1984 Hanahan spent his time at Cold Spring Harbor Laboratory (CSHL). Cohen and Boyer's recombinant DNA technology had initiated a series of discussions as to its safety, and there were strict guidelines for working with bacterial strains and recombinant DNA. CSHL was one of the facilities on the East Coast that had the type of containment facilities set up to do recombinant DNA work.

By experimentation, Hanahan was able to improve on the method used to introduce DNA into bacteria. This, and his theories on the mechanism of DNA uptake constituted the bulk of his thesis work.

Hanahan stayed at CSHL as a staff scientist until 1988. He took advantage of the small, intimate community of scientists at CSHL to explore and develop his interest in other areas of biology. Hanahan became particularly interested in oncogenes and how they worked. This is currently his main research interest.

In 1988, Hanahan accepted a position at the University of California, San Francisco where he is currently a Professor in the Department of Biochemistry and Biophysics and Hormone Research Institute.

Hanahan enjoys playing tennis and sailing; both activities that he first took up while at CSHL. He also chases after his toddlers and grows orchids.