takes one to know one

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(it) takes one to know one

childish A retort used to suggest that the person who has accused someone of being something negative thing is in fact that thing (as if being that thing would help one to identify others of like kind). A: "You're a real jerk!" B: "Yeah, well, it takes one to know one!" A: "I don't want to sit next to her—she's a nerd!" B: "Takes one to know one!"
See also: know, one, take, to
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

(It) takes one to know one.

Inf. You are one also. A: You are a stupid oaf. B: So are you. It takes one to know one.
See also: know, one, take, to
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
See also:
References in periodicals archive ?
IT TAKES ONE TO KNOW ONE: Anfield legends (from top left) John Aldridge, Alan Kennedy, Ian Callaghan, Sammy Lee, Ian Rush and Phil Neal today praised the current crop of Reds stars
However, based on the theory it takes one to know one, Wales on Sunday, in this instance, agrees wholeheartedly with Mr Davies' 'expert' opinion.
. "It Takes One to Know One: Passing and Communities of Common Interest." Critical Inquiry 20 (Summer 1994): 715-36.
His nod to the subject of the book comes in his last sentence, "But then, as I hope to have persuaded my fellow, newly constituted spooks, as we begin benignly to stalk a new Europe, it takes one to know one."
Fair enough, but it apparently takes one to know one: "Hollywood should not be making exploitive violent and exploitive sex films.
"Takes one to know one," Treddy said as he gave her a hug.
Ironically, Arnold commonly warns the clearcutting magnates that environmentalists are driven by a 'cult' kmentality: "Once newly committed people have joined an environmental group, they become True Believers who will fight and die for the cause." I guess it takes one to know one.
Everyone would say, "Well, it takes one to know one," and my credibility would vanish.
It's painfully trite to say it takes one to know one, but in this case it cannot be helped.
Maybe because "it takes one to know one", or do they realise none has the credentials for the job?
And trust me when I say, it takes one to know one here, and I know one when I see one.
The sources said that Lohan has said that she knows her life is "out of control," but doesn't think the precept, "It takes one to know one," is the way to go.
Levine, it takes one to know one. After all, he was one of the first employees of Veritas - rising from engineer to executive vice president there before Symantec bought the company in 2004 for $13.5 billion.
If it takes one to know one, then Forster couldn't have asked for a more glowing reference than the Italian World Cup–winning legend he has studied throughout the formative years of his career.