Nikki Sixx said he learned to have some "empathy" for his father while writing his new memoir, The First 21: How I Became NIkki Sixx.

The Motley Crue bassist reflects on his tumultuous youth and early musical career in his aptly titled new book. Sixx, born Frank Feranna Jr. in 1958, took a Greyhound bus from Jerome, Idaho to Los Angeles at age 17 and legally changed his name to Nikki Sixx shortly thereafter. He ceremonially killed his childhood self in Motley Crue's "On With the Show," which opens with the lyrics, “Frankie died just the other night / Some say it was suicide / But we know how the story goes.”

While writing the book, Sixx learned some shocking truths about why his father left his family while Sixx was just a child. In an interview with Yahoo Music, Sixx said the elder Frank Feranna left home "right around the time that my sister Lisa, who was born with Down syndrome, was sent to a home [by Sixx’s mother, against Sixx’s father’s wishes]. And no one in my family had said that's why he left. My uncles said something may have made Frank, my dad, ‘really angry’ and he left. And you know, my part of that is, ‘Yeah — but he left me behind!’ So, how do I have empathy? And how do I try to look at it from a 10,000-foot view?”

Shortly after arriving in Hollywood, Sixx called his father to ask him for money, only to learn that he had died a couple years earlier. For years, the rocker had a misconception of his father as a hard-living man, but the process of writing The First 21 dispelled that notion.

"About four years ago, I was at my aunt and uncle's house … And I said, 'Can I just, like, ask you something?'" Sixx recalled. "'You know, my mom said' — and this is my mom's sister, Harlene – 'said that my dad was an alcoholic and a womanizer and a drug addict, and he was a bad guy.' So, that's what I thought. Nobody ever contested that. And then I asked them, 'What was my dad like, as far as these things?' And my uncle and my aunt go, 'I don't think I ever saw your dad even have a beer.' I was like, 'Ooh, are you effing kidding me?'"

Sixx will release The First 21 on Oct. 19. His other band, Sixx:A.M., will release their Hits compilation three days later. The group released a lyric video for a new song titled "The First 21" last week.

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