In a Facebook post from November 17, 2013, Mary Cheney, (Liz Cheney’s sister, criticized Liz for holding to the “traditional definition of marriage” in a recent Fox News interview. Specifically, Liz had said, “I love Mary very much. I love her family very much. This is just an issue on which we disagree.”
Mary, who identifies as gay, admonished Liz: “This isn’t just an issue on which we disagree — you’re just wrong — and on the wrong side of history.”
Heather Poe, Mary’s spouse, had originally posted on Facebook that "[Liz] didn't hesitate to tell us how happy she was for us" when she and Mary were married, and “to have her now say she doesn't support our right to marry is offensive to say the least.”

In light of her criticism of former President Trump in early 2021, many critics resurfaced this controversy, arguing that Cheney “sold out her own lesbian sister” to win a Senate seat.