Bill Gates says his three kids never would've gotten away with the hijinks he pulled as a 13-year-old — like sneaking out of the house to write computer code until after 2 a.m.

The future billionaire's rationale for sneaking out was simple: Hardly anyone had a bulky, expensive computer in their home at the time, and he wanted to spend more time figuring the technology out. His parents were too busy with their own careers — his father was an attorney, and his mother was a civic activist — to notice that their teen son was sneaking out of the house, he says.

"I certainly benefited from a little bit of laissez-faire treatment," says Gates.

Gates had lucked into an arrangement with a local Seattle-area company that gave him unlimited computer time, and spent roughly four months focusing heavily on writing software code, according to his new memoir, "Source Code," which published earlier this month. The experience was invaluable to his development as a skilled coder, he writes.

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"We were kids ... none of us had any real computer experience," Gates writes, adding: "Without that lucky break of free computer time — call it my first 500 hours — the next 9,500 hours might not have happened at all."

As Gates became more proficient at coding, he began thinking about possible real-world applications of his new skills — like writing software for personal computers, the idea that launched Microsoft — an epiphany he might have never experienced, if he'd stayed in his bedroom each night, he says.

'Why am I wasting time here when I could be at the computer?'

In the book, Gates writes about some of the freedoms that his open-minded parents afforded him, allowing him to spend hours reading and thinking in his room and letting him go on weeklong hikes in the mountains around Seattle without adult supervision.

At age 13, he started regularly taking a 20-minute cross-city bus to an office to get in some late-night software coding — without his parents' knowledge. "Why am I wasting time here when I could be at the computer?" he recalls thinking.

A local company, Computer Center Corp., had tasked Gates and his friends in the computer club at Seattle's Lakeside School, including his future Microsoft co-founder Paul Allen, with identifying bugs in its programming code. The company gave them unlimited time for writing and testing their own code — including after-hours access — in exchange, writes Gates.

"No one seemed to wonder why a kid was out alone at that hour," Gates writes. He'd sometimes walk 45 minutes home if he missed the last bus of the night at 2 a.m., "rewriting code in my head, tuning out the [University of Washington] students spilling from the bars and coffee shops."

His parents did eventually find out, he notes: "They were like, 'Hey, come on, you've got to get sleep. You're not supposed to do that stuff.'"

As for his own three children, who are now adults, Gates says he'd like to think that he'd know if they snuck out in the middle of the night — something he'd never approve of, as a father. "I definitely was a more observant parent, with huge help from [ex-wife Melinda French Gates]," he says.

His children "all turned out super well," says Gates. "So, I guess, multiple paths to success."

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