In a biography to be published this week, former President George H. W. Bush says that he has “mellowed” on gay marriage.

The father of former President George W. Bush and Republican presidential candidate Jeb Bush is the subject of a biography by Jon Meacham to be published by Random House titled Destiny and Power: The American Odyssey of George Herbert Walker Bush.

According to The New York Times, Bush's evolution on marriage equality is described in the book.

In the late 80's, Bush said that Americans “don't want homosexual marriages codified.”

Two years ago, he and his wife Barbara served as official witnesses at the wedding of a lesbian couple in Maine.

(Related: George H. W. Bush serves as witness at gay marriage.)

In a note given to his biographer this September, Bush, 91, said that he has “mellowed.”

“Personally, I still believe in traditional marriage,” he wrote. “But people should be able to do what they want to do, without discrimination. People have a right to be happy. I guess you could say I have mellowed.”