That's what Mitt claimed in a 1978 interview with the Boston Herald. That is, that he and his father, George Romney, joined in marching with Dr. King. "My father and I marched with Martin Luther King, Jr. through the streets of Detroit." An article by Michael Levenson in the December 21 issue of the Boston Globe refutes this claim, too. I missed it in the Globe. But a friend called to my attention Andrew Sullivan's posting the same day about this false claim. This "marching" is not just a metaphor. It is an out-and-out lie, and apparently a habitual one. That makes good old Mitt a pathological liar. And, of course, given our last two presidents congenital aversion to the truth, this is also a qualification for the office.
Apparently, there are cognate claims all over the web. Here are two:
Joshua Marshall: "My dad sailed with Columbus."
Another: "My mom dated Jesus."
You are welcome to make up others and post them here.