When Silicon Valley tech journalist and entrepreneur Sarah Lacy became a mother, she invited a couple of fellow new parents to her San Francisco home.
"I have a huge TV in my living room and I think we had a baseball game on in the background - we weren't even watching it or interacting with it," she recalls. But then something curious happened; one dad, "another figure in the tech industry", was sitting on the couch, holding his baby, which began looking around the room, and its mother obscured its view of the screen, saying: "No, you're not going to see television at all until you're three years old."
"She thought the baby being on this couch would be permanently damaging to her child," Lacy laughs.
This kind of behaviour is becoming increasingly common as many of the tech world's leading lights, whose products have been used by millions of children the world over, are now intent on curbing their own offspring's screen time. Not content with banning their children's devices, they are now legally stipulating that staff do the same. A report last weekend documented the rise in nanny contracts requiring that Silicon Valley sprogs not only be kept away from their own screens, but that those tasked with looking after them don't use their phones in front of the children, either.
Apple co-founder Steve Jobs was the first tech giant to admit, in 2011, that his own children had not used the recently released iPad created by his company, conceding that "we limit how much technology our kids use at home". And he wasn't alone: Microsoft founder Bill Gates set time limits on screens, banned mobile phones at the table and didn't let his children have them until they were 14, while Mark Zuckerberg implored his baby daughter to "stop and smell the flowers" in an open letter to her which he released last year - one that made no mention of Facebook or even the internet.
Perhaps it's parenthood that makes tech entrepreneurs think differently: or so they say. Instagram founder Kevin Systrom recently expressed hope that the next generation of entrepreneurs could solve the problems of online harassment and bullying, which he failed to stamp out on his own platform; his nine-month-old daughter, Freya, he said, had made him think harder about his own legacy. If others feel the same - and actually translate these concerns into action - it could be a seismic shift for Silicon Valley.
Those at the very top, who were often barely out of university when they had their billion-dollar ideas, are now grown-ups with partners and children. Zuckerberg was still in his teens when he launched Facebook - now he's a 34-year-old father of two. Marissa Mayer, the former chief executive of Yahoo, was not yet 25 when she became employee number 20 at Google. She has since had three children. Jeff Bezos was 30 and newly married when he founded Amazon in his garage. He and his wife are now parents of four.
Yet it is unlikely that this will lead to a crisis of conscience, says Adam Alter, a professor of marketing at New York University and author of a recent book about technology addiction, because it would be "completely inconsistent with the duty they have to their shareholders - to maximise profits.
"For all the advantages they and their kids enjoy - from wealth to education - they don't trust themselves or their kids to be able to resist the charms of the very products they're promoting." It would be "silly" to expect them to change, he says. "The best we can do is to try to uncover these hypocrisies and air them publicly."
It might seem counterintuitive, but low-tech parenting makes sense in Silicon Valley. One of the schools popular among tech workers, the Waldorf School of the Peninsula, based near Google's Mountain View campus, believes that exposing children to technology before the seventh grade (when they are 12 or 13 years old) "can hamper their ability to fully develop strong bodies, healthy habits of discipline and self control, fluency with creative and artistic expression and flexible and agile minds".
Beverly Amico, of the association of Waldorf Schools of North America, says tech leaders send their children to the school in part because keeping young children away from tech in the classroom cultivates the attributes they like to see among their staff - creative thinking, resourcefulness and perseverance.
Tech-world parents also know too much. Susan Hobbs, Chief of Staff at security firm Cloudflare and a former venture capitalist, "completely banned" her daughter, now 16, from using social media, "which actually became a bit of a point of contention. I would leave town and she would download Instagram. So I changed the restrictions on her phone so the App Store [to download it from] didn't even show up".
She was eventually won over by a PowerPoint presentation in which her daughter (successfully) demonstrated that she was mature enough to use it.
Most of the big social media founders have yet to see the full impact of their own creations on their children, who are largely too young to use social media. But other Silicon Valley workers have discovered a taste for activism recently, mounting a series of successful high-profile campaigns, from thousands of Google employees protesting against the company's contract with the US Department of Defense (it later dropped the deal) to Susan Fowler Rigetti, an engineer at Uber, speaking out about sexism last year, which forced out its chief executive, Travis Kalanick.
As talented tech employees show an increased willingness to leave - or publicly embarrass - companies that fail to fulfil their ethical standards, perhaps this is the kind of 'disruption' (the buzzword adopted by so many founders) that Silicon Valley actually needs.