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Editor's note: Ruben Navarrette is a CNN contributor and a nationally syndicated columnist with the Washington Post Writers Group. Follow him on Twitter @rubennavarrette.

San Diego, California (CNN) -- Republicans portray themselves as the party of family values. Yet, in Wyoming, one prominent group of right wing kinfolk will spend the holidays embroiled in a family feud.

You don't get to choose your family. Still, family members might choose a destructive lifestyle that puts them at odds with loved ones. They make others uncomfortable, and hurt those who love them. These people are often thinking only of themselves, and they haven't considered the consequences of their behavior.

Liz Cheney is one of these people. And the destructive lifestyle she has chosen is that of a politician.

The Republican Senate candidate from Wyoming is running to the right of Republican incumbent Sen. Mike Enzi. And because that might not be so easy to do, whenever the challenger offers an opinion on a topic, it's difficult to know if she's speaking from the heart -- or pandering to the lowest common denominator.

An independent political group calling itself the American Principles Fund, which is defending Enzi, recently launched an ad attacking Cheney for opposing a constitutional amendment to ban same-sex marriage and supporting the decision of the State Department to give benefits to same-sex partners of employees.

This week, while calling on Enzi to denounce the ad and labeling it "gutter politics," Cheney stood by those earlier positions. During an interview on "Fox News Sunday," she said:

"I don't believe we ought to discriminate against people because of their sexual orientation. If people are in a same-sex relationship and they want their partner to be able to have health benefits or be designated as a beneficiary on their life insurance, there's no reason we shouldn't do that."

Nonetheless, that ad puts Cheney in a tight spot, and given that Wyoming is a very conservative state and given that she's trying to position herself on the far right of the spectrum, she can't be seen as soft on same-sex marriage.

Thus, in the same interview, she made clear that she doesn't favor allowing same-sex couples to wed and that she supports "the traditional definition of marriage."

It's a position that Cheney has long held. That is part of the problem. In a country where, as public opinion polls make clear, the opinion of so many Americans on same-sex marriage is rapidly evolving due in large part to the fact that young Americans consider this a nonissue, it would have been good to see some personal growth from Cheney.

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Besides, she should tread lightly on this subject. Why? Because blood is thicker than votes. And because Michael Corleone was right, and -- even in the rough and tumble of politics -- you "don't ever take sides with anyone against the family."

And, for the Cheney family, this issue is personal. Liz's sister, Mary, is in a same-sex marriage and has two children with her wife and longtime companion, Heather Poe.

"I love Mary very much. I love her family very much. This is just an issue in which we disagree," Cheney said on "Fox News Sunday."

Mary Cheney wasn't having any of it. Not long after the interview, she posted this rebuttal on Facebook:

"Liz -- this isn't just an issue on which we disagree -- you're just wrong -- and on the wrong side of history."

Mary also shared a post by Poe, who was likewise bothered by Liz's comments. It read:

"I was watching my sister-in-law on Fox News Sunday (yes Liz, in fifteen states and the District of Columbia you are my sister-in-law) and was very disappointed to hear her say 'I do believe in the traditional definition of marriage....

"Liz has been a guest in our home, has spent time and shared holidays with our children, and when Mary and I got married in 2012 -- she didn't hesitate to tell us how happy she was for us.

"To have her now say she doesn't support our right to marry is offensive to say the least."

Here is what Liz Cheney missed: To many proponents of marriage equality, the very idea of "traditional marriage" is offensive. You see, tradition is the antithesis of progress. It was once tradition that women didn't have the right to vote, and African-Americans used separate restrooms, and U.S.-born Mexican-Americans were swept up in immigration sweeps. Those things had to change, and they did. In those instances, Americans decided that tradition should take a back seat to things like fairness, justice and equality.

This year, Christmas dinner at the Cheney house is bound to be awkward. The kids are fighting, and that sort of thing always hurts the parents most of all.

"This is an issue we have dealt with privately for many years, and we are pained to see it become public," Vice President Dick Cheney and his wife, Lynne, said Monday in a statement.

They insisted that Liz Cheney has "always treated her sister and her sister's family with love and respect, exactly as she should have done." And, they said, "Compassion is called for, even when there is disagreement about such a fundamental matter."

The Cheneys know something about compassion. Over the years, they have been remarkably graceful and supportive toward Mary Cheney and her family. Dick Cheney has challenged conservatives in his own party by saying that gays and lesbians should be allowed to marry and that -- despite calls for a federal ban on same-sex marriage -- the issue should be handled at the state level.

I know something about what Liz Cheney is going through. As recently as 14 years ago, I was opposed to same-sex marriage and supported the watered-down alternative: civil unions. I thought this was a battle that wasn't worth fighting and that gay activists should focus their attention elsewhere.

However, my younger brother, who is gay, wouldn't let me get away with it. He challenged me. He told me I was wrong. He forced me to be a better person. I changed my view, and came to understand that Americans can't have a two-tiered system, where some of us enjoy the right to marry the people we love while our brothers and sisters and cousins are denied that right, based on nothing more than sexual orientation. It's discrimination with all its ugliness.

In the end, this is where we should arrive. Not just because you love your brother, or your sister, but because, just as importantly, you love your country. And you understand what America stands for above all else: freedom.

For all of us. Or none of us.

The opinions expressed in this commentary are solely those of Ruben Navarrette.