Classic-fit, two-button navy wool suit ($1,095) and Sansforth button-down shirt ($165), Burberry. 1155 Connecticut Ave. NW; burberry.com. Royal Oak self-winding chronograph watch, Audemars Piguet ($34,600). Lenkersdorfer Fine Jewelers, Tysons Corner Center; lenkersdorfer.com

Long and lean, with ramrod-straight posture, a snow-white complexion and a regal halo of silveryblonde hair, Tim Gunn, in the flesh, recalls a ’20s vaudevillian playing a prim professor. He moves back and forth and side to side during the Capitol File cover shoot, performing a graceful box step as he raises his hand to his chin, drops it, then pulls his glasses down the bridge of his nose and cocks an eyebrow just so. He’s relaxed without being silly; studied without seeming rigid. When the shoot wraps, Gunn dispenses hugs and European-style double kisses to each member of the crew, declaring the experience “joyous, simply joyous.” It’s clear that the feeling is entirely mutual. “I say to people, treat everyone with respect and dignity,” Gunn says later, decompressing between bites of a tuna sandwich. “You never know what opportunities may exist—or where that person you were obnoxious to may land!” The 57-year-old Project Runway star and chief creative officer for Liz Claiborne dispenses etiquette and fashion advice in his new book, Gunn’s Golden Rules, and isn’t shy about sharing his opinions on topics ranging from the wild (reality TV and The Real Housewives of D.C.) to the practical (good posture). Over the course of 90 minutes, he gave us a refreshingly uncensored take on the Michelle O. versus Jackie O. debate, the need for new Congressional page uniforms and why he’ll never design his own line.

Given that you became famous through Project Runway and have spent almost three decades of your life living in Manhattan, it’s easy to assume that you’re a New Yorker.
No, I’m the product of five generations of Washingtonians!

What was it like for you growing up in DC?
My father was an FBI agent, and my mother began the library at the CIA. Once she got pregnant with me, she became a real estate broker. Washington is such a transient town that there’s always someone buying and selling. So it was fun being with her and going to her listings. She’d always cart me around with her to see inside a lot of big politicos’ houses. I can’t remember any names, but there were a lot of diplomats. But I remember the delegate from Samoa because the whole place was decorated like Trader Vic’s.

I have to say I feel very lucky to have grown up in Washington. It provides so much culture. Although downtown was very different when I was growing up; it wasn’t gentrified the way it is today. There are places people are living [now] where I wouldn’t even have driven my car, let alone walked around because of what could happen at the stoplight. It’s changed dramatically.

As a child, were there any signs that you had a future in fashion?
Well, my favorite toy growing up was Legos. I would build and unbuild over and over again. I spent every dime of my allowance on Lego blocks. I also had a plastic castle that came with toy soldiers, and I personalized it; I made little balsa wood furniture and covered it with felt, put curtains on the windows. And of course the soldiers looked pretty blah, so I made little costumes for them. I was a very solitary kid, so I spent a lot of time by myself—and didn’t dislike it, which worried my parents.

Were you shy?
I had a very bad stutter. When I get tired, it still comes out.

That must have been awful.
I’m such a happy, lucky guy. But I would not have said that when I was growing up as a teen, which devastates my mother, because she thinks she did something wrong or that my father did something wrong.

For a public figure, you maintain privacy about your personal life. Is that difficult?
You know, people always say to me, “People don’t know very much about you. And you seem very open, but you’re very private.” It’s not that I don’t want to talk about it, but I mean, unless asked, I don’t go there. I don’t even assume anyone wants to know anything. One of my golden rules in my book [Gunn’s Golden Rules, which came out in September] is, Learn how to keep your mouth shut. People who say, “Oh, I just need to get this off my chest….” Well, maybe you do, but maybe the person you’re telling doesn’t need to know this. It’s like indiscretions in a marriage: “Oh, I’ll feel so much better if I tell my wife.” Well, you may, but will she?