Looking at photographs of a young Siobhan Copland, you might see similarities to a fresh-faced Meghan Markle at about the same age: both girls sporting a curly halo of frizz above wide grins.

Since then, much has changed. Siobhan is now happily in a long-term relationship with Colin, 34, a data analyst, and her lustrous, silky hair now falls poker-straight to her collarbone.

Meghan, of course, is Prince Harry’s bride-to-be, with a stellar acting career, impressive dedication to philanthropy, and work as a UN women’s advocate all strings to her bow — and a head of hair so smooth and shiny it gives Kate Middleton a run for her money.

But as Siobhan attests, keeping hair this straight and sleek is a daily struggle that takes up an astonishing amount of time.

Meghan Markle (pictured) revealed she uses the semi-permanent hair straightening treatment, Brazilian Blowout

Like Siobhan, who has an English mother and a father from Grenada in the Caribbean, Meghan is proudly mixed-race — her father is Caucasian and her mother is African-American — and since her teenage years has undergone a rigorous hair-straightening regime.

In 2011 Meghan said: ‘My mom is black and my dad is Dutch and Irish, so the texture of my hair is densely curly. I’ve been getting Brazilian blowouts for a couple of years.’

A Brazilian blow-dry is a semi-permanent straightening treatment where a mix of keratin (a key structural protein in hair and nails) and formaldehyde is applied to the head to penetrate hair cuticles, smoothing the hair shaft. The results can last up to four months and the treatment can cost from around £100 to £350.

Siobhan describes hair relaxing treatments, blow-dries and hours battling with straightening irons — not to mention a considerable financial outlay. At one stage she was spending £150 a month on blow-dries, products and fake hair extensions, and estimates she has parted with thousands over the years.

‘Of course Afro hair is beautiful, and if I could rock a big round Afro I would, but I think you need a certain personality to pull off that look,’ she says. ‘I feel sexier with straightened hair.’

Whatever our background or cultural heritage, the appearance of our hair has always been deeply connected to women’s sense of confidence and self-esteem. And many feel pressured to look a certain way, even from childhood, internalising social messages that say their ‘natural’ look isn’t good enough.

This can be a particular problem for black and mixed-race women who may have experienced prejudice based on their Afro hair.

Undoubtedly for those with curly hair, embracing its natural state would save a lot of hassle but, for Siobhan, as for so many women, her hair represented far more than window-dressing. It was a means of self-expression, of changing how she felt about herself.

Meghan Markle (pictured age 12) describes her hair texture as densely curly

Her earliest memory relating to her hair is a painful one. She recalls being five when her mother laughingly started calling her ‘mothball head’ while trying to brush out her thick curls.

‘You’d see the hair before you saw me,’ says the 31-year-old dating coach from Essex. ‘When I comb it out I still look like a lion. My mother, who is English and Irish, struggled to brush it. She would be vicious, raking through it, with me in tears. My head was always bruised.’

Siobhan recalls how her ringlets gave rise to unkind nicknames in the playground. ‘I used to wear my hair in a high curly ponytail and was nicknamed pineapple head by a boy at school,’ she explains. ‘I didn’t think I wasn’t beautiful but I was aware there was something about me that made me different.

My head was always bruised - Siobhan Copland

‘I grew up in East Ham, a multicultural area of East London, but there was no one else in my primary school class who had hair like mine. Everyone else had long, blonde silky hair.

‘I remember my first crush with another mixed-race boy. I really thought I was in love with him but he went for the girl with the long blonde hair. I thought it was because she had nicer hair.’

These incidents left a deep mark. So, at 13, with a bit of a prod from her mother, Siobhan had her hair ‘relaxed’ for the first time, a process whereby chemicals are applied to hair to change its structure and relax the natural curl. The results can last for months, but it takes hours and can cause scalp burns.

Siobhan bought a chemical relaxer, hung her hair over the bath at her aunt’s house, gritted her teeth and set to work. It burned her scalp, took hours and the chemicals smelt fishy. But she says it was worth it.

Siobhan Copland (pictured age 31) began using chemical relaxers to change her hair texture at age 13

‘Finally, my hair blew in the wind. I suddenly became popular with boys. I had new hair and a new confidence.’

She recalls how she would hide her hair’s natural state from her boyfriends. She describes an episode in her 20s when her mother gave the game away by lambasting her for using hair extensions to make it look straighter.

‘It was a moment of total humiliation,’ she says.

Now, however, her partner Colin sees her with her hair straight, curly and anything in between and is a fan of the natural look.

Semoy Lee-Pow, 45, from Enfield, has sacrificed a lot in pursuit of straight hair. The former healthcare assistant used to spend three hours every two weeks painstakingly washing, straightening and blow-drying her mane into submission, then avoiding moisture like the plague to make the results last.

I had new hair and a new confidence

‘I would do it at home, taking breaks when I got too knackered. Other girls say my hair is so beautiful, but I say, “No, it’s not, you don’t know the stress I go though to get it to look like this”.’

But the feeling it gives her walking down the street is, says Semoy, worth the effort. She started straightening aged 16 to look more ‘polished’ for office jobs, and never stopped.

‘With curly hair I just don’t feel confident. There were times when, if I couldn’t get a blow-dry, it would really upset me.

‘Hair has always been a big thing in our family. My father is half-Chinese and Trinidadian and my mother has Indian and Portuguese ancestry. When I was small my mum’s main thing was giving me ringlets, which drove me crazy.’

Now she has professional blow-dries twice a month, costing £60, as chronic pain has stopped her performing the ritual herself. She also tried Brazilian blow-dries.

Siobhan Copland (pictured as a child) says she spent years hiding the natural state of her hair from boyfriends

But her 21-year-old daughter, Rihanna, has Afro-Caribbean hair and forgoes straightening treatments, a fact that’s making Semoy feel differently about the practice — and given her a sense that society is changing, too.

‘I look at her beautiful hair and it has encouraged me to do the same. Times have changed so much since when I was younger. Afro-Caribbean hair is a lot more accepted in society now.’

As well as aesthetic or cultural pressures to straighten, which can leave women feeling like they are not good enough unless they match a certain ‘ideal’ look, the physical damage from prolonged and intensive straightening treatments can be severe, especially for those with black or mixed-race hair where stronger chemicals are required to alter its texture.

School was just easier to deal with having straight hair - Marcia Polimis

Much of this damage is irreversible, as Jimmy Campbell, a stylist and salon owner in London, sees first hand.

‘At worst, the chemicals stop the hair growing,’ he says. ‘It’s why women wear wigs and weaves. Look at someone like Naomi Campbell. She has no hairline.’

Marcia Polimis, 41, a client service manager from Maidenhead, has been using Brazilian blow-dries, hair irons and extensions for decades. The damage this has caused has irrevocably altered the texture of her hair.

‘I’ve had it straightened for so long that once I wash it and it is in its natural state, it’s just a bush. It has pulled out the curl I have and is now somewhere in between an Afro and fluff. At 41, I am past going out with it like that.’

Marcia Polimis (pictured age 41) says she began chemically relaxing her hair at age 16 in order to fit in with others at school

So, she doesn’t, having decided she prefers to carry on straightening her hair. Marcia was 16 when she first had her strands chemically relaxed, wanting to fit in at a school near where her family lived in Middlesex in the early Nineties. With an English mother and West Indian father, she says her Afro attracted unwelcome attention.

‘There were only a few mixed-race people at my school. It was a time when there was racism. Chemically straightening my hair was a way to fit in.’

Although she says she didn’t suffer ‘too much’ racial abuse, there was the odd comment that cut to the bone. ‘When I was 11 I got the whole “go back to where you came from” thing. It gives you a complex.

‘Throughout your teenage years it can affect your sense of self, of how you look and who you are. School was just easier to deal with having straight hair.’

Whatever race you are, getting your hair done makes you feel better about yourself

These days, she says, she straightens her hair simply out of choice. ‘I don’t care at all. I am who I am. Whatever race you are, getting your hair done makes you feel better about yourself. When it’s freshly done it gives you a psychological boost.

‘There will be a point when I will stop, but right now it is something I do for myself. As society is today, a lot of girls want to conform to what’s in the media but that’s never been me.’

For Hilary Sheikh, 54, a retail assistant from South-West London, anything less than perfectly straight hair feels like a compromise. For 35 years she has kept her naturally curly hair sleek and smooth at a cost of around £1,200 a year.

‘It makes me feel beautiful and look younger. When I have it straightened people forget I am an old lady.’

Marcia Polimis (pictured as a child) claims she straightens her hair for herself now rather than in a bid to conform

While Meghan continues to fly the flag for ironed-flat hair, elsewhere there is a growing movement of women deciding to go natural.

Amir Delijani, a hair technician from celebrity salon Daniel Hersheson specialising in Afro-Caribbean hair, has seen a sea change when it comes to curls versus smooth and straight.

‘There has been a real drop in people using chemical straightening and more young ladies are going for the natural look, especially if their hair is curly or Afro. They don’t mind the free-frizz look. It doesn’t matter if hair isn’t straight and smooth any longer.

‘It’s a lot down to fashion. In the late Sixties and early Seventies the first hair relaxers — permanent or semi-permanent chemical straighteners — took off in the U.S. because they were the latest thing and people are attracted to change. Now people are looking for something different.’

And there is a groundswell of support for positive messages around black and Afro hair. Initiatives such as Project Embrace, a campaign to stop women altering their natural hair, are calling for more Afro hair to be used in advertising campaigns.

In November last year Oscar-winner Lupita Nyong’o received a public apology from a magazine after it airbrushed and smoothed a front cover image of her hair without her permission. The same had happened just a month before when pop star Beyonce’s sister Solange, also a singer, objected to her hair being touched-up on another magazine’s front cover.

Every woman knows that hair is a great deal more than face-framing strands of keratin. For Siobhan Copland, some persuasion from her partner and a confidence born from entering her 30s mean she has learned to accept her natural curls.

Having a one-year-old daughter, Bella, has also left little time for straightening. But more than that, she wants to set a good example.

‘I tell Bella every day I love her curls. I hope she will grow up always loving hers, and I definitely won’t be taking her to get it relaxed. I want her to feel confident in her natural state.

‘Every young girl I see on social media looks the same — a bunch of Barbie dolls, with long, smooth hair, small waists and nose jobs. That wasn’t happening when I grew up. It’s really sad. We should look like individuals.

‘I would hate for Bella to grow up thinking she had to look a certain way. Now I am a lot more relaxed about my hair as I’m with someone who accepts me and my natural beauty, whether that’s a lion’s mane or sleek and shiny.’