Rob Kardashian's transgender curiosity stems back to 2012.

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During his appearance as a judge at the Miss USA pageant in 2012, the Keeping Up With The Kardashians star questioned Miss Rhode Island, Olivia Culpo, about a possible transgender contestant.

"Would you feel it would be fair that a transgender woman wins the Miss USA title over a natural-born woman?" Kardashian, 28, asked, according to an Us Weekly report on Friday.

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At the time, no one had heard about Bruce, now Caitlyn, Jenner's plans to become a woman, which had reportedly been a years-long struggle for the father of six.

"I do think that that would be fair," Culpo, the current girlfriend of Nick Jonas, replied. "But I can understand that people would be a little apprehensive to take that road because there is a tradition of natural-born women, but today where there's so many surgeries and so many people out there who have a need to change for a happier life, I do accept that, because I believe it's a free country."

Following Jenner's interview with 20/20 in April, Kardashian took to Twitter, where he applauded his step-father for going public with his desire to become female.

To see Rob Kardashian's appearance on Miss USA 2012, check out the video below.