The Princess of Wales has a close-knit relationship with her family, with Kate's parents Carole and Michael Middleton residing at the family home in Bucklebury. The property is just a short drive away from Kate's home at Adelaide Cottage, and they no doubt will be supporting Kate following her cancer diagnosis.
Since their daughter began dating Prince William after meeting at university, the Middletons have remained respectful and have rarely given interviews about their royal connections.
Carole has shared some sweet anecdotes about being a grandmother to William and Kate's three children, including that they each get to decorate their own Christmas trees during the festive period.
Meanwhile, Kate is incredibly close to her younger siblings, having shared a flat in Chelsea with her sister Pippa Middleton before Kate's marriage to William.
The Princess's brother and entrepreneur James Middleton has also revealed how supportive his big sisters were when he was struggling with depression, telling of how Kate and Pippa attended therapy with him and he likewise returned the gesture following Kate's health news, sharing: "Over the years, we have climbed many mountains together. As a family, we will climb this one with you too."
Here's everything you need to know about the Middleton family...
Carole Middleton
Born to Ronald and Dorothy Goldsmith on 31 January 1955 in Perivale, London, Carole grew up and was educated in Southall. She has a younger brother, IT recruitment consultant Gary Goldsmith, who recently appeared on Celebrity Big Brother.
After her A-Levels, Carole worked as a shop assistant for John Lewis before getting a job as a flight attendant at British Airways (BA), where she met flight dispatcher and her future husband, Michael Middleton.
Carole and Michael married in 1980 in a low-key ceremony, with Carole later revealing to The Telegraph: "I found the venue, organised the wedding breakfast, the bonfire and chilli con carne in the evening."
The bride wore an off-the-shoulder boho-style wedding dress, which she later lent to her daughter-in-law Alizee Thevenet for her nuptials to James in September 2021.
Carole and Michael welcomed eldest daughter and future royal Catherine two years later on 9 January 1982. Their second daughter Pippa arrived in 1983, followed by son James in 1987.
The Middletons lived in Amman, Jordan from 1984 to 1986, where Michael worked as a manager for BA.
Carole founded her party supplies business, Party Pieces, in 1987, with all three children helping out at the company through the years. But Party Pieces was sold to entrepreneur James Sinclair in June 2023, after falling into administration.
Michael Middleton
Michael Francis Middleton was born on 23 June 1949 to Captain Peter Middleton and Valerie Middleton (née Glassborow) in Leeds. His father served as a RAF pilot during the Second World War and even flew alongside the late Duke of Edinburgh as a co-pilot on a two-month flying tour of South Africa in 1962.
His mother Valerie was a VAD nurse and code-breaker during the Second World War.
Michael's ancestry has connections to the aristocracy, with his grandfather Richard Noel Middleton and his wife Olive, moving in royal circles in the 1920s.
Following in his family footsteps, Michael attended Clifton College in Bristol and later attended the University of Surrey. He began working at British Airways in the 1970s, where he met his future wife Carole. He later helped Carole to run the family business, Party Pieces, in 1989.
Pippa Middleton
Philippa Charlotte Middleton was born on 6 September 1983 at Royal Berkshire Hospital in Reading. Like her older sister Kate, Pippa was educated at St Andrew's School in Pangbourne, before moving to Downe House School and then Marlborough College.
She graduated from the University of Edinburgh with a degree in English Literature and in 2022, she earned her postgraduate master's degree in Physical Education, Sport and Physical Literacy from University of Wales Trinity Saint David.
Pippa briefly worked in public relations and wrote a fitness and wellbeing column for Waitrose's magazine. She also penned a book, Celebrate, a one-stop guide to entertaining, in 2012.
Like her sister Kate, she shares a passion for sport and has taken on a number of challenges, including a 3,000-mile cycling race across America, the Bosphorus Cross-Continental Swimming Race - a 6.5 km swimming competition in Istanbul and a 47-mile swim-run competition in Sweden.
She almost stole the show for her figure-hugging bridesmaid dress at William and Kate's wedding in 2011.
In May 2017, she married hedge fund manager James Matthews – older brother of Made In Chelsea star, Spencer Matthews.
After Pippa acted as Kate's maid of honour on her big day to Prince William in 2011, Kate got to return the favour and was pictured adjusting her little sister's veil as she arrived at the church on her wedding day. Prince George and Princess Charlotte had starring roles in the bridal party.
Since then, Pippa and James have become parents to three children – Arthur, Grace and Rose.
James Middleton
James William Middleton arrived on 15 April 1987 at the Royal Berkshire Hospital in Reading. Like his older sisters, he was educated at St Andrew's School and Marlborough College. After dropping out of university, James founded his own cake-making business as well as a mail-order personalised marshmallow company, boomf.
As well as being a mental health advocate, James credited his late dog Ella, who passed away in 2023, with helping him through his depression.
The entrepreneur regularly shares updates about his brood of dogs on his personal Instagram account and in 2020 he launched Ella & Co, a mail order dog food company that offers freeze-dried, raw, organic dog food.
James began dating French financial analyst Alizee Thevenet in 2018, later telling The Telegraph that he had his late dog Ella to thank for him meeting his future wife at the South Kensington Club in Chelsea.
He wrote: "Ella was lying at my feet under the table; realising she might want some water, I trusted her to take herself over to the water bowl across the terrace.
"However, she made a beeline for Alizée. Rather embarrassed, I went over to apologise and bring Ella back," he explained. "But Alizée thought I was the waiter and ordered her drink while continuing to stroke Ella, who at this point was on her back lapping up the attention.
"Little did I know, but I had just met my future wife, all thanks to Ella. If I hadn't trusted Ella, I wouldn't have brought her to the South Kensington Club and she wouldn't have been able to say hi to the woman who became my fiancée."
James and Alizee tied the knot in Bormes-les-Mimosas in 2021, having previously postponed their wedding twice due to the pandemic. The couple welcomed a son, Inigo, in October 2023.
In March 2024, the 36-year-old announced that he had written his first memoir, Meet Ella: The Dog Who Saved My Life, which is scheduled to be released on 26 September 2024.