Dustin Lance Black’s autobiography “Mama’s Boy” (Alfred A. Knopf, $26.95) focuses less on his showbiz career and more on his early formative years. As a painfully shy kid, he survived physical abuse, Mormon repression and Texas-style military conservatism, to become the Oscar-winning screenwriter of “Milk” (2008). He has used his fame to campaign for human rights and equality, helping to overturn the discriminatory Prop. 8 in California and working successfully to get the Supreme Court to declare marriage equality for LGBT citizens. Black, who is married to Olympic medalist Tom Daley, with one son, is developing multiple projects, including “Under the Banner of Heaven” as a miniseries at FX, and a feature film about activist Bayard Rustin. Black was first mentioned in an Oct. 25, 2000, review of pop opera “Bare” at the Zephyr Theatre in Los Angeles, when he was a set designer, praised for his “inventive sets,” alongside William Kaufman.

You’re known as a writer, but your earliest mention was as set designer.

That was my first time in Variety, and the reviewer was positive, so I thought, “All right, here we go!” Actually, there was a direct line from that stage design to my standing on an Oscar stage. Damon Intrabartolo, who wrote the book and music for “Bare,” knew I had aspirations to write. He asked me to do the book for his next project, about the Names Project AIDS Memorial Quilt. He found Cleve Jones, who conceived of that giant quilt commemorating the dead. Doing that play meant I got to meet Cleve Jones, who was Harvey Milk’s protege; that gave me a foothold to write an original script about Harvey Milk.

When you were a kid in Texas, you seemed to hate performing in the Jingle Bell Band.

Before second grade, I didn’t speak to anyone except my immediate family. At one point, a teacher was concerned about me and sent me to academic club, which was actually a debate club. She was also the drama teacher, and explained debate is more difficult, because you need to come up with your own words in front of people; but if I went into the theater department, I could use other people’s words as I stood in terror on the stage. I was being encouraged to step out of my shell.

In your book, you write about Salinas, Calif., at age 13: “That community theater, the Western Stage, saved my life.”

We loaded up my mom’s Malibu Classic and escaped a physically abusive situation and landed in Salinas. The Western Stage dramaturg invited me to join their apprentice program. I felt immediately safe with her, which rarely happened. And that changed the course of my life. One thing that made a big difference: It was the first time I encountered people who were openly gay. I knew I was and I found that incredibly hopeful. They didn’t have horns, like Mormon Prophets said; they didn’t seem like criminals, like Texans said; they weren’t mentally ill, like talkshows of the day said. All of a sudden, the theater, which seemed so terrifying in my Jingle Bell Band, now seemed like a place of refuge. At the Western Stage, I was apprentice to a theater director who said a good director needs to be a Renaissance storyteller; aside from working with actors and playwrights, you need to know props, lights, sets. I really enjoyed set design.

And then film school?

I was accepted at USC, but [President] Bush Sr. closed many Army bases, so our family was broke. Every school counselor told me the University of California was more affordable, but impossible, since they only accepted 15 each year. I went to community college for two years. I was living in Section 8 housing in a rough corner of Pasadena, working at JC Penney and heading to community college each day. I had no car since I was T-boned by, literally, a little old lady in Pasadena. My car was pushed into a Del Taco drive-thru, and my knee went through the dashboard. For a long time I was on crutches, but I dared not complain, because my mom was on crutches her entire life. When I look back, I’m now impressed with that kid. There was nothing I wouldn’t do to get to UCLA film school. Once I was there, it was well worth it.

Against all odds, you were accepted to UCLA?

I was one of the 15. I went in as a director. The greatest thing for me was meeting Bob Rosen, who ran the archives and taught classes. He taught me I was free to interpret what I saw in any film, and I should learn from what I saw onscreen, not worry about the director’s intent. He said, “Something brilliant onscreen may have been a happy accident on the day they filmed that scene; we don’t know what they intended, so why bother?” Also, Bob Rosen, I found out later, was an openly gay man who had worked in civil rights and helped move the country forward.

But how did you return to theater and set design?

After graduating from UCLA film school, of course nobody immediate greenlights your first feature film, so I figured maybe I could slowly move my way up, and there was more of a ladder to climb in an art department. I got PA jobs, which I really enjoyed. On “Bare,” I was working with Billy Kaufman, who’d worked on “X-Files.” It was never my aspiration be a production designer, but there was actually a ladder you could move up. And what a great way to learn about filmmaking as I wrote my own screenplays at home after a long day on the set.

Do you give advice to people starting out?

I say to my assistants all the time: “Do your very best at every job you get. If your job is to get coffee, do an exemplary job at getting coffee. You don’t know the doors that may open up because they will learn that you give a damn.” I really gave a damn about those sets at a 99-seat theater with “Bare.” The composer said, “This guy cares and is detail-oriented,” because I was invested in the exact curve of the metal that I cut for the front of that stage, for example. “So maybe he will give that same attention to detail in his writing.” So the next major step in my career was directly linked to my work on that play.