If Liz Cheney, whose bid for the Senate has always had a stench of extreme opportunism, wants to discuss traditions and values, I’m all for it. Let’s start here: Isn’t there a tradition of close-knit family members’ taking care not to wound one another? Is there not value in that?

From the moment that Liz decided, from the perch of her longtime home in the Virginia suburbs of Washington, to act the part of an honest-to-goodness Wyoming resident and challenge an incumbent senator (and family friend) from that state, she must have known that the issue of same-sex marriage would come up. It is, after all, a prominent thread in the news. It’s also a prominent thread in stories about her family, given that her father, Dick, bucked his party to become an early Republican supporter of same-sex marriage, and given that her lone sibling, Mary, has a female spouse.

She must also have entertained speaking out against it, because that’s what she ended up doing on Sunday, on Fox News, saying that she believed “in the traditional definition of marriage.” And she must have foreseen that this would pain Mary, who was married last year and whose two children are being brought up with the understanding that their family has the same dignity as any other.

But she plunged forward anyway, disregarding the inevitable discord. As Jonathan Martin reported in The Times, Liz and Mary aren’t speaking to each other now, and there’s a long shadow over the Cheneys’ holiday get-togethers.