He was raised by a psychologically-minded mother and a politically active father. On his father’s side, Peter is a fifth generation northern Californian. His great-great-grandfather Nathan Coombs founded the town of Napa in 1848 and was the first of four generations of Coombs/Dunlaps to represent the Napa Valley in the California legislature ending with his father John Dunlap. While previous generations were conservatives, Peter's dad was a liberal Democrat, passing legislation protecting the environment, endangered species, allowing farm workers the right to unionize, and implementing land-use regulations, including the founding of the Coastal Commission.