In his upcoming book, Levi Johnston — former boyfriend to Bristol Palin and father to her son, Tripp –  said former Alaska Gov. Sarah Palin offered to adopt the couple’s baby as her own to “avoid a scandal,” according to the Associated Press.

Due for release Sept. 20 — the AP purchased the book — “Deer in the Headlights: My Life in Sarah Palin’s Crosshairs” details Johnston’s relationship with the eldest Palin daughter and her family.

In one instance, he said, Johnston and Bristol Palin wouldn’t allow the former GOP vice presidential candidate to pass their child off as her own and that Sarah Palin did not want Tripp to call her “grandma.”

He also claims that Bristol Palin got pregnant as revenge for her mother getting pregnant with son Trig. She said, “Let’s get pregnant,” he writes in the book.

Johnston says he was “too dumb” to use protection while dating Bristol Palin but that having a baby was “what she wanted,” according to the AP.

The two ended their relationship shortly after their son’s birth. Eighteen months later, they got engaged and sold their story to the tabloids but broke things off for good after Bristol Palin said Johnston had admitted to impregnating another woman.