If you’re related to one of the actors, the subject of a play is often beside the point.

Take A.R. Gurney’s A Light Lunch at the Flea Theater in Tribeca until January 25th. It is, as the title suggests, a light affair. Having lambasted George W. Bush in two previous works, Mr. Farnsworth and O Jerusalem, the staunchly liberal Mr. Gurney offers a reappraisal of the president’s rise and fall, going soft on him as his global influence wanes.

The play takes place in a restaurant in New York City’s theater district, where a Texas attorney named Beth (Beth Hoyt) is looking to option the newest script by a playwright named A.R. Gurney. Her anonymous client heard it was anti-Bush, and wants it shelved. Mr. Gurney’s agent, the youthful Gary (Tom Lipinski, my brother as it happens), prevents this by explaining that the script is actually pro-Bush.

I gathered this much, but little else, since it’s hard to follow the plot when your brother is the lead actor. I might as well have been watching a different play.

On the rare occasion that I see Tom Lipinski (i.e. Tommy) perform onstage, I think, “Why is he acting like that?” A normally sarcastic and understated young man, under the lights he becomes wildly expressive, punctuating each sentence with charged and florid gestures. He grips other actors by the lapels and wrestles with them for kitchen knives. His voice drops an octave. I have to sit in the back of the theater, partly so he doesn’t make eye contact with me and laugh, and partly out of fear.

Watching a friend or relative act can be a disorienting experience. Not unlike a child seeing his father without a mustache for the first time. I mention fathers intentionally, because that’s who my brother at first appears to be onstage: our father. An expressive and dramatic man by nature, he was the subject of constant imitation in our youth. And since most plays call for “adult” characters, it was only natural my boyish 26-year-old brother take our dad’s mannerisms to the stage. Indeed, as the New York Times critic Charles Isherwood pointed out in his review of A Light Lunch, “Gary…looks scarcely old enough to order a glass of pinot grigio.”

The first time I saw him act in a play, my brother simply channeled our dad. An Oedipal twist was added when his character, an aging high school hero gone wrong, kills his father through a bit of small town political racketeering. At the play’s close, he walked past me in the aisle, crying his eyes out while leading his dead father’s funeral procession. The tears were convincing. I was wary around him for weeks.

Rightly so, perhaps, since acting frequently resembles lying. To say you’re a good actor is a little like saying you’re a good liar, that you’re capable of manipulating the emotions of innocent people, even your own kin.

When Tommy began taking acting classes in New York City, I sometimes caught him acting around me. Darkly furrowing his brow, say, or speaking in an over-earnest tone. I’d accuse him of acting, and he’d vehemently deny it, because the accusation was so harsh. It was like I’d called him a con man.

Meanwhile, I took pride in the fact that I couldn’t act, as if I were too authentic to behave like someone else with conviction. He was being fake; I was keeping it real.

But to think this way was to presume that I had a genuine self, and that my brother did not. Many people complain that actors seem fake or unnatural. But it’s their job to inhabit other selves, which may gradually wear away their belief in a fixed self, a “real me.”

Novelists might understand the actor’s predicament. As Philip Roth writes in The Counterlife: “All I can tell you with certainty is that I, for one, have no self…. What I have instead is a variety of impersonations I can do…. I am theater and nothing more than theater.” With this in mind, actors may be in a sense more “real” than non-actors. By trade, they confront the unsettling reality that a “real me” may not exist.

Consequently, if you share a genetic makeup with one of the actors onstage, a play as apparently whimsical as A Light Lunch can get sort of heavy.

From the Flea’s back row, I kept searching Gary for signs of Tommy, as the child looks for a familiar nose in the mustache’s absence. Halfway through, speaking to a waitress named Viola, Gary says without irony, “You go, girl!” Tommy wouldn’t say that, I thought. Nor would he say “Oh boy oh boy oh boy!” upon hearing surprising news, as he does when Beth confesses her client’s identity.

At one point, however, Gary does a funny impression of George W. Bush, which I recognized as Tommy’s impression of Dana Carvey doing George Bush Sr. on Saturday Night Live. And then, when Beth declares that she’s attracted to him, Gary looks away and mutters “Oh sure, oh sure”—exactly the way Tommy would have said it!

I was the only one in the theater who laughed. It was, for me at least, the funniest part of the play.