Pennsylvania's Gov. Tom Corbett compared same-sex marriage to incest today, angering advocates for gay rights.

In an interview with a local Pennsylvania television station, the Republican made clear he thought that comparing gay marriage to a union between two 12-year-olds was "inappropriate."

He probably should have stopped there.

But Corbett, who is up for re-election in 2014, went a step further during an interview today with a CBS affiliate.

"I think a much better analogy would have been brother and sister, don't you?" Corbett said, offering his own analogy for gay marriage.

Corbett made the comment after the interviewer asked the governor to respond to a comparison between gay marriage and the marriage of two children made by lawyers for the state of Pennsylvania in a recent legal brief.

"It was an inappropriate analogy, you know," Corbett said of the lawyers' statement.

Corbett's comparison of gay marriage to incest unleashed a wave of criticism from advocates for gay rights.

Ted Martin with Equality Pennsylvania, which advocates on behalf of lesbian, gay, bisexual and transgender people, called the governor's remarks "shocking and hurtful" and asked him to apologize, according to the Associated Press.

The outpouring of criticism prompted the governor to apologize.

"My words were not intended to offend anyone," Corbett said in a statement later in the morning. "If they did, I apologize."

His comment today comes as Corbett is facing a tough re-election campaign and suffering from low overall approval ratings.

A June Quinnipiac poll, 48 percent of the state's voters surveyed said they disapproved of the job Corbett was doing. Notably that's 5 percent higher than the percentage of Pennsylvanians who disapprove of gay marriage, according to a January Quinnipiac poll.

Gov. Tom Corbett at Dow Chemical's new research-and-development facility in Collegeville, Pa., July 31, 2013. (Matt Rourke/AP Photo)