And they now have an equally famous family, with daughter Blue Ivy, 13, and seven-year-old twins, Rumi and Sir

But Beyoncé’s mother, businesswoman and fashion designer Tina Knowles, tells me she “worries about the fame” impacting her grandchildren.

“If I had my first choice, they would not have to deal with the things that they have to deal with as kids,” she says.

Knowles, 71, says for now, the children are not too exposed to it.

“But one day they’ll read the ignorance that people put out there about them, the lies and all of that,” she says. “And I do worry about that.”

Despite those pressures, she says Beyoncé and Jay-Z – who are notoriously private about their home life – are doing an “amazing” job as parents.

“The truth is they spend abnormal amount of time with their children and they have great relationships with their kids,” she says.

“And they’re just great parents. I don’t think you could ask for better parents.”Knowles is speaking to BBC News ahead of the publication of her new memoir, Matriarch.

It covers her childhood in Texas, her daughters’ rise to fame and her later years, as a grandmother.

Knowles now has four grandchildren, including Julez Smith, the son of her younger daughter, singer-songwriter Solange. She also considers herself a grandmother to former Destiny’s Child singer Kelly Rowland’s children.

She says that she sees all her grandchildren regularly, describing them as “one of the biggest joys in my life”.

“[Blue Ivy and I] have a very close bond,” she says of her eldest granddaughter.

“I’m so happy that she feels like she can talk to me,” she says, adding that Blue Ivy is always giving her advice about taking care of herself.

“She’s my beauty guru. She’s my manager,” she says.

I’m intrigued by this, and ask why she calls the 13-year-old her manager.

“Well, I don’t call her my manager. Everybody else calls her my manager, because she’s bossy. She’s a little Capricorn like me. So we have that bond.”

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Knowles grew up in 50s and 60s Galveston, the youngest of seven.

In her book, she talks about the harassment her family faced, including from the police.

“There was a lot of racial tension,” she tells me. “And I think some things have changed, but I still think that black people are more susceptible to police brutality [and] being stopped.”

She met her now ex-husband, Mathew Knowles, in Houston and the pair went on to have two daughters, Beyoncé in 1981 and Solange five years later.

Beyoncé, she writes, was “not an easy baby”. Nursery rhymes did not cut it (“she cried louder” to drown out Mary Had A Little Lamb), but jazz music would soothe her.

As a child, Solange was a “social butterfly” but Beyoncé was shy. “She walked into every classroom trying to be invisible,” Knowles writes.

She says at the time, her daughters – and all little black girls – were being “bombarded” by messages from mainstream culture that they were “less than”.

But Beyoncé was always singing, and Solange’s talent emerged early on too.

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