“You are who you pretend to be (in politics)”

Kurt Vonnegut, Jr. (1922-2007) wrote in the introduction to his novel Mother Night (1961):
 
“We are what we pretend to be, so we must be careful about what we pretend to be.”
 
“You are what/who you pretend to be, so you must be careful about what/who you pretend to be” is a popular paraphrase of the words. “You are who you pretend to be” became a saying about the Internet since the 1990s.
 
“But in politics, you are who you pretend to be” was written by Michael Kinsley in Time magaine, September 6, 2007. “You are who you pretend to be” has only infrequently been used to describe political candidates, however.
 
   
Wikiquote: Kurt Vonnegut
Kurt Vonnegut, Jr. (November 11, 1922 – April 11, 2007) was an American novelist known for works blending satire, black comedy, and science fiction.
(...)
Mother Night (1961)
We are what we pretend to be, so we must be careful about what we pretend to be.
. Introduction (1966)
. Sometimes misquoted as: Be careful what you pretend to be because you are what you pretend to be.
 
Google Books
Hunter and the Ico
By Eric Sauter
New York, NY: Avon
1984
Pg. 81:
“Oh, shit,” the Mormon said, shaking his head. “Remember Kurt Vonnegut’s advice,” I told him. “You are who you pretend to be, so be very careful who you pretend to be. You thought you were Jimmy Cagney but you’re really Pat O’Brien.”
 
Google News Archive
24 August 1990, Daily News (Bowling Green, KY), pg. 6B, col. 2 ad:
You are who you pretend to be.
JAMES BELUSHI
CHARLES GRODIN
TAKING CARE OF BUSINESS
(A film—ed.)
 
Google Books
Masterplots II Poetry Series
By Frank N. Magill
Pasadena, CA : Salem Press
1992
Pg. 652:
His line might be translated as “let being be the end of appearance,” or — to paraphrase Kurt Vonnegut, Jr., in his introduction to Mother Night (1961) — be careful who you pretend to be, because who you pretend to be is who you are.
 
Google Books
21 November 1996, Southeast Missourian (Cape Girardeau, MO), “Letters from Home” by Sam Blackwell, pg. 2A, col. 3:
A few days after the concert, someone on the TV show “Sunday Morning” was talking about Kurt Vonnegut and one of his famous aphorisms: You are who you pretend to be.
 
Google Books
Culture of the Internet
Edited by Sara Kiesler
mahwah, NJ: Lawrence Erlbaum Associates, Publishers
1997
Pg. 147:
As one experienced player put it, “you are the character and you are not the character both at the same time.” And “you are who you pretend to be.”
   
4 August 2000, Lexington (KY) Herald-Leader, “Burgoo: Something to stew over,” pg. A8:
In politics, you are who you pretend to be.
   
Time magazine
God as Their Running Mate
By Michael Kinsley
Thursday, Sept. 06, 2007
(...)
It will be amusing if Romney is done in by a fear of his religious values because, as near as we can tell, he has no values of any sort that he wouldn’t happily abandon if they became a burden. But in politics, you are who you pretend to be.
     
Google Books
The Almost True Story of Ryan Fisher: A Novel
By Rob Stennett
Grand Rapids, MI: Zondervan
2008
Pg. 6:
You are who you pretend to be.
So be careful who you pretend to be.
KURT VONNEGUT JR.
 
New York (NY) Times
We, Robots
By JONAH LEHRER
Published: January 21, 2011
In 1995, Sherry Turkle, a professor of the “social studies of science” at M.I.T., published a book about identity in the digital age called “Life on the Screen.” It was a mostly optimistic account, as Turkle celebrated the freedom of online identity. Instead of being constrained by the responsibilities of real life, Turkle argued, people were using the Web to experiment, trying on personalities like pieces of clothing. As one online user told her, “You are who you pretend to be.”