Esther Wojcicki is telling me about her favourite places to go shopping. "I love H&M and Zara!" she exclaims, with a broad grin. "Oh — and Costco! Costco is fantastic. I've bought some great jackets there."
This is not the conversation I was expecting to have with Esther, 78, who's the mother of two of America's richest women — Susan Wojcicki, 50, CEO of YouTube, with an estimated fortune of £385 million, and Anne Wojcicki, 45, co-founder and CEO of direct-to-consumer DNA testing company 23andMe, who's worth £542 million.
Anne is also the ex-wife of Google co-founder Sergey Brin, the 14th richest man in the world with a £40 billion fortune. Esther's middle daughter, 48-year-old Janet, is no slouch either as an associate professor of epidemiology.
So stellar are the Wojcicki sisters that Esther — who's still working at Palo Alto High School in California's Silicon Valley, where she's taught journalism for 35 years — has written a book How To Raise Successful People, to share her secrets with other parents.
Yet Esther is clear that success has nothing to do with status or wealth. "Success doesn't mean being a CEO or having a powerful job," she says, sitting in her not particularly glitzy London hotel. She is over here to promote her Global Moonshots programme, showing teachers how her parenting techniques can transform their classrooms.
So would she have been satisfied if her daughters had all been stay-at-home mothers (there are ten grandchildren, aged between 19 and two weeks old)? "That would have been fine with me, as long as they were happy."
As the mother of two daughters, aged 12 and 14, I approached Esther's book convinced it would be packed with complacent stories of how she taught her offspring Mandarin aged two, bassoon at three, before they qualified as Olympic-level gymnasts aged four.
But Esther, who is warm, funny and not remotely smug, is horrified by scary Tiger Mother methods — the tough parenting rules of fellow American Amy Chua, who once threatened to burn her daughter's soft toys when she failed to master a piano piece.
"I admire Amy Chua's devotion to her daughters," Esther says measuredly. "But I think her approach failed to instil a sense of passion or independence in them. The key to happiness is a sense of power over your life, and I think a lot of people feel they don't have that. They feel controlled by their families, that they're doing things they don't personally want to do to make somebody else happy."
She also has no time for "helicopter" parents, who do everything for their children, as personified by Desperate Housewives' Felicity Huffman — the star recently pleaded guilty to paying bribes to help her daughter win a place at a top university.
In contrast, Esther's maternal style (Stan, her husband of nearly 60 years and a retired physics professor, left the majority of parenting to her) involved being as hands-off as possible.
From the ages of five, the girls walked to school alone; as soon as they could count she allocated them a budget and let them organise the family food shop.
She let all three quit learning a musical instrument and refrained from comment when, on graduating from Yale University, Anne announced she wanted to be a nanny. (With no maternal nagging, she changed her mind and bagged a fancy finance job.) "As a parent, you have to keep it zipped," Esther says.
This relaxed style — dubbed Panda mothering, first by her German publishers then worldwide in honour of those notoriously lazy mammals — is great news for mums like me, who'd far rather binge-watch old episodes of First Dates than help my eldest make a Taj Mahal model for her history homework, or supervise the youngest's piano practice. So is Esther giving me permission to do nothing? She shakes her head, laughing. "Panda mums aren't lazy. What they do is give children scaffolding to let them go free. Instead of always intervening, you only help when they need it."
Lax as I am, even I worry about my children's overuse of mobile phones, a bugbear Esther didn't have to contend with. So should Panda parents allow our children to be glued to screens 24/7?
"You have to compromise," Esther counsels. "Let children have two hours screen time, with one hour on apps you think are important, then, during the other, they can play on ones they think are important."
There's one no-no, however — violent video games such as Fortnite. "Games like that are full of killing. They have a negative effect on the subconscious. I ban them!" Fortnite's not an issue in my house. Instead I battle nightly over whether my girls should watch Love Island. "Oh, that sounds quite tame," says Esther, when I described it to her. "My kids were addicted to Little House On The Prairie."
Um, I think, Prairie's far more wholesome viewing. "Does Love Island contain overt sex?" Esther asks. "If so, I'd say: 'There's a certain number of hours in the day and a certain number of years in your life. Is this what you really want to spend your life doing?'"
Oh, Esther, if I had a pound for every time I've tried that, I'd be richer than your daughters, but never mind! In any case, all this advice comes too late, as Esther says, "your control over your child is over by the time they're 14".
After then, all you can do is "respect your kids' ideas and preferences, otherwise communication shuts down, just when they most need your support".
Clearly, Esther's girls have fulfilled all her dreams of being independent, yet, like every mother, she worries about them.
She was devastated by Anne's divorce in 2015. She split from Brin, the father of her two children, after he had an affair with a British colleague (and allegedly friend of Anne's) Amanda Rosenberg, causing a huge scandal in Silicon Valley and an alleged fallout between Brin and his Google co-founder Larry Page.
Gossip had it that Brin grappled with Anne over her — very Wojcicki — determination to pursue a "normal" family life, with him changing nappies and being home for dinner. It all went against Esther's key belief that parents should do everything to avoid divorce.
"We've sanctioned divorce to such a degree, a lot of us break up for silly reasons," Esther says. "Of course, I'm not talking about people in abusive relationships, but if someone's had a one-night stand that's regretful, but is it a reason to throw away a whole lifetime of memories? If you divorce, the model kids see is: 'I can't work things out. I have no grit.'"
As a non-interfering mother, did she try to help Anne salvage the marriage? "That was really tough. I tried politely, but what can I do? Mothers are supposed to be quiet, right? I wish Anne and Sergey had had my book to read, put it that way. I'd have loved to have helped more, but you have to butt out."
The couple are reportedly now both single and, at least, still friends. Esther's also had to hear criticism about Susan, who is frequently attacked (often by upset parents) for doing too little to regulate YouTube's sometimes unsuitable content.
"I do worry about Susan. She has a tough job," she says. "She understands the dark side [of the internet], that there are people making videos about hate or pornography and, in her heart, she is trying to make it the best place for everybody.
"She's not Superman — though she might be a superwoman.
"She's down-to-earth; lives in a normal house; drives a regular car, but we're all like that.
"We don't take exorbitant vacations, we fly on commercial planes not private jets. Material things don't make you happy."
Frugality runs through Esther's veins. The daughter of Russian immigrants, she grew up in an impoverished agricultural community in California. "Having very little taught me to find solutions to get the things I wanted," she says. "I only had one pair of shoes, so I polished them every night to make them look like new."
Today's children, she thinks, possess far too much. "Electronic games, Lego sets, hi-tech bikes, rooms so full of stuff they can't use it all. It means they never learn the real value of working hard for something." The Wojcicki girls all worked unglamorous jobs as students. "And my grandkids have all worked from the age of 14, in shops and restaurants. They're not given large allowances; they're not bought cars and they have to help around the house," Esther says.
Such behaviour is highly unusual in Esther's billionaire-studded neighbourhood, but she's never cared what the neighbours, or anyone, thinks.
Her attitude was shaped by tragedy: when she was eight her 16-month-old brother, David, accidentally swallowed a handful of aspirins. Three hospitals turned him away, suspecting the family couldn't afford their medical fees. A fourth hospital admitted him, but it was too late and he died.
"It taught me to be sceptical of authority and always find out the truth myself," she says.
Later, she suffered two miscarriages before becoming pregnant with Susan. Doctors offered her new medication to help her "hold on to the baby", but Esther refused to take it. "The doctor threw me out and refused to take care of me. It was awful."
The drug was thalidomide, with around 10,000 babies worldwide born with defects as a result of their mothers taking it. "Imagine!" Esther exclaims. "If I hadn't been such a rebel, I'd have been the mother of a child without a limb."
She instilled this questioning approach in her daughters, who were by no means always angels.
When they were 16, 15 and 13, Esther and Stan went away for a weekend, leaving them home alone. They returned to a spotless house but, at work, Esther spotted a pupil dressed in her clothes. "I discovered the girls had thrown a party for 100 people and, when guests spilled drinks on themselves, they'd given them some of our clothes to wear," she recalls.
So the Wojcickis aren't perfect? "Oh, no! In fact, when my book came out I found out there'd actually been a second party. They'd never told me until now!"
Esther chuckles uproariously. As I said, she's not smug at all.
This article was first published in the Daily Mail.