Much like the husband or wife of the prime-minister, the children are un-elected and unpaid - and their lives have been changed forever. For some Prime Ministers, their children were in their 20s, so had no need to live in the home, while Boris and Carrie Johnson had son Wilfred, and daughter Romy were born while living at No.10.
Soon, Prime Minster Liz Truss will move into Downing Street, alongside her husband Hugh O'Leary and teenage daughters 16-year-old Florence and 13-year-old Liberty. The pair are said to be thrilled by the prospect - with Liz Truss previously describing them as "very excited" at living in one of the world's most famous addresses
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It's a big transition - living in No.10, or realistically No.11 - where every prime minister from 1997 has lived because its living quarters are larger.
They'll have a small group of adults who have lived there with their parents, who can advise them on what to expect. Samantha Cameron previously said she was glad her children had left No.10 before they became teens.
It was easier to protect them from the "weirdness" of that world when they were small, but she imagined it would be tougher living in that semi-public home when older.
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"The flat is very private but you're living above the shop," she recalled. "All the security arrangements make it incredibly hard for people to come and go," she said. "You are living in a fortress. It's not normal."
The girls are said to be planning sleepovers at the home, that leads on to St James's Park, and will get to visit sprawling country estate Chequers, which boasts a heated swimming pool.
It's an odd set-up for children, living above a bustling office filled with politicians and senior government workers, and Liz Truss will have to decide where they can go.
For instance David Cameron said that, for his children, there was "no distinction between home areas and work areas, it was all theirs. It was one giant labyrinth to explore"
And Kate Fall, Cameron's deputy chief of staff, recalled: "I can remember at least once when the Cameron childcare fell apart and Florence had to join our 8.30am meeting. She sat on my lap, sucking a mint slowly."
Meanwhile Tony Blair's son Leo's toys were scattered throughout the house, wrote former Times editor Peter Stothard in his book 30 Days, a diary following the PM in the run-up to the Iraq war.
Recalling a war cabinet meeting that he attended, he wrote that "in the half-darkness, the rooms resemble the site of a hastily nished children's party. The Thomas the Tank Engine train set is overflowing its box.
"At the bottom of the stairs, as though beguiling the prime minister to stumble, is a baby-sized drum kit with BAND in large letters on the bass".
But others were keen to keep them separate, with George Osborne initially opting to stay in his Notting Hill home when he became chancellor.
And John Major 's wife Norma lived separately from PM John Major with their three children when he served as PM.
Now sources have told the Guardian that Truss may opt for a mix of two - with husband Hugh O'Leary keen to keep a low profile
Friends of Truss wonder whether the new incumbents might combine the two approaches: "She won't be able to resist" moving into Downing Street rather than staying in Greenwich, one friend told the paper.
But Mr O'Leary may commute back to their home daily, or find an office in Westminster to travel out too.
Thursday nights are said to be pizza nights in the Truss household - so that might be an occasion where the work/life boundary is blurred.
Truss has previously said she enjoys cooking the family Mexican, Chinese and Sichuan food, and told the press that they hosted a "family Come Dine With Me thing” over lockdown, too.
Staff used to looking after the Johnson's toddlers may find they have to switch it up if Florence, 16, and Liberty, 13, move in. But the teens are excited, with Truss revealing: "My younger daughter keeps asking would she be able to have sleepovers if I get into No 10,” before she was elected.
"Clothes everywhere”, "kids running with pancake pans”, and "like a bomb has gone off”, one friend is said to have used to describe the Truss family home, in Greenwich.
Truss says her children have "been brought up on politics, adding previously that her duo are her "unpaid therapists” who she “pretty much tell[s] them everything”.
This includes acting as the PM'S stylist, with Truss saying Liberty, 13, is "very into the idea of a pop of colour” and tries to get her to shop at shops like New Look.
And Frances has been helping out on the PM's digital campaign, with Truss revealing in July: ""[Frances has] done a computing GCSE so she’s helping out on that."
