Singer Adam Lambert says in a new special airing Sunday that he realized he was gay in the sixth grade.

In the VH1 Behind the Music special, the 29-year-old American Idol season 8 runner-up also says he felt “ashamed” to be gay.

“I think when I was in about the sixth grade, that's when I first realized that I was probably not the same as the other boys,” Lambert is quoted as saying in the 1-hour special by The Hollywood Reporter. “I was kind of in denial for a while and it was all in my head. And to me it was a deep secret. I was just not ready to talk about it with anybody.”

“I think at that age it was something that I was ashamed of, because it was so different,” he added.

The VH1 special goes on to cover Lambert's coming out gay on the cover of Rolling Stone, and features interviews with Lambert's mother and Idol winner Kris Allen.

(Related: Adam Lambert had worried he was too openly gay.)