Here's a shocker. Barbara Bush, one of George W. Bush's twin daughters, will endorse gay marriage today, despite the fact that when her father was president, he pushed for a constitutional amendment to ban it. 

The 29-year-old Bush videotaped a message asking for New Yorkers to legalize gay marriage as part of New Yorkers for Marriage Equality and the Human Rights Campaign.

Barbara Bush is the latest daughter of a prominent Republican to support gay marriage. Meghan McCain, the daughter of John McCain; and Mary Cheney, the daughter of former Vice President Dick Cheney, are also supporters of same-sex unions.