show one's true stripes

present singular third person shows one's true stripes · participle present showing one's true stripes · past showed one's true stripes · participle past shown one's true stripes · US also participle past showed one's true stripes

1. idiomaticTo reveal one's real beliefs, sentiments, or character, especially through one's behavior.

   "My fear is that Bill Ford is showing his true stripes as just another short-sighted auto executive with no interest in the environment."

   2005 July 12, Danny Hakim, “With Sierra Club's Help, Ford Pushes a New Hybrid”, in New York Times, retrieved 21 Mar 2013

   2 more examples

   Fidel Castro showed his true stripes again—as if they weren't indelible enough already—by letting his MiGs shoot down two of three unarmed Cuban-exile planes off Havana's coast on Saturday.

   1996 February 26, “Editorial" Against Change in Cuba”, in Miami Herald, retrieved 21 Mar 2013, page 14A

   “Now they're showing their true stripes,” Iimmy Fioretos said. “The Turks wanted to invade all along. That malarkey about ‘protecting the Constitution’ was just a pretext.”

   2002, Jeffrey Eugenides, Middlesex (2011 reprint), p. 363 (Google preview)

   Synonyms: show one's true colors