Prince Harry turns 36 on 15 September, an age which may not seem like a milestone, but which is likely to have an impact on the royal – as it is the same age his mother was when she was killed in a car crash.
Princess Diana had turned 36 just eight weeks before she died in Paris, as she and her partner Dodi Fayed fled paparazzi attention.
In 2017, Harry told The Daily Telegraph: "I can safely say that losing my mum at the age of 12, and therefore shutting down all of my emotions for the last 20 years, has had a quite serious effect on not only my personal life but my work as well."
Just a few weeks on, he will be preparing for one of the most poignant birthdays he has ever marked.
Other people who have experienced the milestone of becoming older than their parents have described how their parent became “frozen in time”.
Writer Tamsin Eva explained in HuffPost: “Your parent has to be older than you. If you become older than they were, it's as if they are no longer the parent. Almost like a disquieting role reversal where you become the parent of the parent.”
On turning 46, the age her mother died, author and life coach Nina Collins wrote: “The model that I had – memories, at least, of my mother in her 30s and 40s –i s no longer relevant.
“From her I learned everything I know about being a mother, running a household, living with mild depression and being glamorous. She taught me all that. But she can’t teach me about what’s next, because she never got there.”
Harry has spoken on a few occasions about the effect the death of his mother had on him, and it has been linked to his decision to step back from senior royal duties earlier this year.
Speaking to ITV in South Africa while on royal tour, he said: “I think being part of this family, in this role, in this job, every single time I see a camera, every single time I hear a click, every single time I see a flash it takes me straight back so in that respect it's the worst reminder of her life as opposed to the best.”
Along with other members of the Royal Family, Harry has marked particular anniversaries of his mother’s death over the years, which experts say can be a difficult part of the grieving process.
Sam Tyrer, managing director of Co-op Funeralcare, said: “The death of a parent is a traumatic experience, and one that is especially distressing for children. In the UK, a parent of children under 18 dies every 22 minutes.
“Grief affects us all in different ways and at different times. The grieving and bereavement process is not short, and is exceptionally personal and unique.
“In time, we learn to live with grief, but often significant dates and milestones, such as birthdays and becoming a parent, can be the most difficult times for those that are bereaved, especially when a parent has died early.”
Harry of course faced a much more public time of grieving than most 12-year-olds who lose a parent. Not only was Diana’s death headline news for months, but he had to walk behind the coffin at her funeral, something he said would be unlikely to happen in recent years.
After revealing he had counselling to deal with his grief, Harry said: “My mother had just died, and I had to walk a long way behind her coffin, surrounded by thousands of people watching me while millions more did on television.
“I don't think any child should be asked to do that, under any circumstances. I don't think it would happen today.”
Harry has followed in his mother’s footsteps, both in his royal work and in some of the aspects of his personal life as an adult.
In Angola on tour last year, he walked the same path through a minefield as his mother had 22 years earlier.
And he, Meghan and Archie live in the same US state that Diana was reportedly considering moving to before she died.
In an interview in 2016, with Good Morning America, Harry said: “We will do everything we can to make sure that she's never forgotten and carry on all of the special gifts, as such, that she portrayed while she was alive.
“I hope that my mother’s talents are shown in a lot of the work that I do.”
As Harry prepares to celebrate his birthday with a new chapter of his life ahead of him, he may be feeling sadness for all that his mother missed out on.
A Sue Ryder bereavement counsellor said: "Losing a parent is an incredibly traumatic experience. Raw feelings of grief can become less intrusive over time but certain events can cause painful feelings to re-emerge or even emerge for the very first time.
“Grief changes as life changes - as with any milestone in life - reaching the age a parent was when they died can bring up old and new feelings of grief.
“Individuals may have feelings of guilt for the life experiences and events that they have had that their parent didn't. This may prompt recognition of other losses, for example, the fact that their parent was never able to be a grandparent. It can also highlight just how young their parent was when they died and intensify the feelings of unfairness that exist within bereavement.”