As a new father myself I am sensitive to Mary Cheney's argument, but it's not about the baby, is it? It's about the values of her father's (and presumably her own) party and what they represent. Dick Cheney is the second most powerful man in the world (and arguably, the first most powerful) and is by extension the leader of (neo) conservative Republicans in the United States. Central to their political platform is the "sanctity" of marriage and the "protection" of family. To them that means "no homos allowed."
"This is a baby," Cheney said Wednesday at a forum sponsored by Glamour magazine. "This is a blessing from God. It is not a political statement. It is not a prop to be used in a debate by people on either side of an issue. It is my child."
I agree and I sincerely hope she and her partner of 15 years have a healthy, happy baby. But unfortunately for her, she's in politics. And politics is policy and the policy promoted by the Republican party does not support her personal stance nor that of millions of gay Americans. When you're an integral part of the Vice President's office and his party actively works to strip the rights of millions of Americans and you happen to be in that minority group, you can't remove the personal from the political. Politics is not an abstract idea, it is the application of policy that affects real, breathing people—yes, even your kids.