United Kingdom, April 18 -- Josh Gad's life "spiralled" after he discovered that he had a secret half-brother.

The 44-year-old star has recalled how he started behaving in a "destructive" manner after being sworn to secrecy by his father about the enormous revelation.

Josh - who has penned the new memoir 'In Gad We Trust: A Tell-Some' - told the 'Bullseye' podcast: "I spiralled. I started getting catastrophic grades in school.

"I remember there was a day where... I was being destructive. You know those lighters in the car that you used to push down to light a cigarette or something? My mother had one of those lighters in the back and I pushed it down, and I remember burning the leather on her car seat. She was like, 'What the hell are ...