Dax Randall Shepard is born in 1975 in Milford, a suburb of Detroit, Michigan, to Laura (LaBo), who works at GM. His mother is of French-Canadian and Belgian descent. His father, Dave Robert Shepard, Sr., is a car salesman, and an alcoholic:
He loved to eat. Holy shit could he eat. Of all of his addictions, and there were many (drugs, alcohol, cigarettes, sex, cars, houses, shiny things), eating was his number one. He never did get a handle on that vice. He could hunker down in front of the TV for hours, nibbling with comma-inducing ferocity the entire time. Nothing in the pantry was safe. He would come up with the most counter-intuitive combinations of food. Like a true alchemist, he’d put salsa on oatmeal, or smother frozen waffles with a can of black beans. He was like a perpetually stoned, pregnant woman. No permutation of ingredients was out of the question; anything was possible. It was a sight to behold.
He graduates from Walled Lake High School in 1993.