Jillian Lauren recalls the moment she first saw her son, Tariku, in a photograph.

He was seven months old and, in the image sent by the adoption agency, he was a "wildly gorgeous boy, with huge brown eyes and his whole hand in his mouth".

From that moment, she says, she knew he was the one: "There was no question in my mind. I felt, 'This is why we've gone through all this.'" What she and her husband, Scott, had gone through was a journey, spanning almost a decade, starting with the creeping realisation of her own infertility, then an assault course of treatments and alternative remedies, and finally the marathon process of adopting a child from Africa.

It is a rollercoaster ride that the American author will hilariously and painfully describe in a one-woman show, Mother Tongue, coming to the Edinburgh Festival Fringe this August – a story which ended, in February 2009, at an orphanage in Ethiopia. There, she and Scott sat with fellow adoptive parents and waited, as one by one their names were called out and they were summoned to ascend the stairs and meet their children for the first time. When they were handed their son, he "looked at us sceptically", but then reached out his hand for Scott's face, as if to wipe his tears. "Or maybe he just liked Scott's gold tooth - It was love at first sight."

Tariku came from Ethiopia, currently the boom destination for adoption, and the country of origin of Angelina Jolie's adopted daughter Zahara. It's estimated that there are 145 million orphans in the world, and four million in Ethiopia alone.

Yet international adoption remains a contentious issue. At one end of the spectrum are critics like the Ethiopian-born poet Lemn Sissay, who was brought up in the north of England by a white couple and says "taking a child from another culture is an act of aggression". At the other are policy-makers who point out that a child is far better in a family than an institution, regardless of what culture he or she comes from. Meanwhile, in the pages of gossip magazines and newspapers, it often seems like the adopted child is a celebrity accessory, worn, draped over the shoulders of Jolie, who has adopted three, or in the arms of Madonna. Such was the media griping about Madonna's adoption of two children from Malawi, that Dr Jane Aronson, a New York paediatrician specialising in internationally adopted children, was prompted to praise Madonna, saying: "That woman spun jewellery off her tits for years and now she's come back as a mature adult to do one good thing in her life that's unselfish."

In fact, Lauren does not believe there is anything particularly "good" about adopting. "Adoption," she says, "isn't a charitable endeavour – it's just one way to make a family. It's a wonderful way to make a family, but it's no better or more altruistic than any other." Mother Tongue is the story of how she, an adopted child herself, assembled that family.

Lauren, who wrote Some Girls, a sensational memoir of her time in the harem of Prince Jefri Bolkiah of Brunei, has had a colourful life and is no stranger to controversy. The journey which would ultimately take her to Ethiopia and the adoption of Tariku began 12 years ago when, at the age of 29, she met her husband, Scott Shriner, a musician from the band Weezer, and, on their first date, he told her that he was "looking to have kids". When, after they had got married two years later, things didn't happen quite as easily as expected, she started "charting and paying attention to optimum days". "I think nobody expects to have fertility issues," she says. "I thought that only happened to women in their 40s who are hedge fund managers and who have left it too late."

Thus began a five-year process of trying to conceive, which was, she says "the most emotionally harrowing I have ever experienced". In Mother Tongue, she lists some of the treatments she experimented with: "Acupressure, chiropractic, reiki. I quit dairy, I quit sugar, I quit meat but then this herbalist told me no, I should be eating meat so now I'm eating meat. I took out my naval ring because it was apparently obstructing the flow of my chi. I tried this exotic psychedelic thing with a shaman from Peru and that was cool ... Charting ovulation, Chinese herbs, pagan rituals, yoga, breathing. Tarot, creative visualisation, homeopathics, hypnosis, ayurvedics, Kabala, colonics, counselling, crystals. Wraps, fasts, meditation, muscle testing, magnets. Maoris."

Her infertility was never medically explained, and towards the end of the process, she began to believe that she was being punished in some way. This feeling reached a peak when she visited some Maori healers, who had been recommended to her. She recalls: "My friend had said her baby had been breech and they had turned it right around. It had popped right out in the middle of the living room." When she went to see them herself, at the home of a "Vedic astrologer" who greeted her at the door with dogs dressed in lederhosen, she recalls the experience was "confusing and surreal and physically very painful". "I felt like I was broken. I had ruined my body through drugs and alcohol, through sleeping with the wrong people, through having an abortion. I thought I was getting a message from God that I was unfit to be a mother."

Lauren's show is not an examination of the practical reasons and debate around adoption, but a personal narrative, one coloured by her current private belief that, whether biological or adopted, we get the children we are meant to. "I feel there is a metaphysical component to adoption and having kids more generally. We are souls drawn together." This sense of destiny is there, even in her description of how she ended up choosing to adopt from Ethiopia. She had met a woman who had done so, and while looking at her photographs she was overwhelmed by a sense that "this had to be the way".

International adoption is a practice that is often clouded with controversy. Reports of trafficking, corruption, the selling of babies and even of parents turning up to claim their kids back after they were stolen, have long dogged the practice, and led to the US freezing adoption from some countries, including Guatemala and Vietnam. This, along with recent policies in Russia and China of focusing more on domestic adoptions, and the impact of the economic crisis, has led to a plummeting in the number of international adoptions from 45,000 in 2004 to 25,000 last year. But aside from these darker issues, there has also been, over the past 20 years, disapproval of the adoption of black and ethnic minority children by white parents, both domestically and internationally.

That view, however, is changing. New guidance in the UK, where our domestic adoption levels are in crisis and a black, Asian or ethnic minority child is three times less likely to be adopted, is that social services should allow white couples to adopt black and ethnic minority children.

Lauren, in fact, is well placed to understand this issue of culture and identity, since she was an adopted child herself. The daughter of a WASPish ballerina from Chicago, adopted into a Jewish family, she notes the way in which she has "something unique to offer an adopted child because I know what it's like to live with identity that has so many loose ends flying around".

On a corkboard in her office, Lauren has three photographs pinned up. One is of her adoptive mother, another her birth mother, a third of her with Tariku's birth mother. "Tariku," she says, "comes into my office and we talk about it and he says 'that's my birth mother'. He feels really bad for my husband because he only has one mother." For her, the important thing is that, from the start, he has "a dialogue" about it. She recalls how, when she was growing up, her own birth mother was "so unspoken of, that I felt I couldn't ask questions, couldn't be curious. Even now my mother will say 'nothing happened before you came to us'. But it is another piece of my story what happened before then. My son also has a narrative that is valid and I honour it."

Nevertheless, parenting Tariku is not without its challenges. Like many adopted children, he exhibits trauma-related behaviours, and is, she points out "dysregulated". "Sometimes," she describes, "there is no reasoning with him. We have to physically pin him down because he would hurt someone or himself." However, as Lauren points out: "No one is guaranteed an easy ride with children, whether you grow them in your belly or adopt them."

"Adoption," Lauren acknowledges in her blog, "was the solution for our family, but it is not the solution for Ethiopia". The country is using it as a method of dealing with its four million orphans – but the infant children like Tariku that most US and European parents want are relatively few by comparison with the swathes of older children. However, there are individuals who benefit from the process. And, as Lauren points out: "There is no question that it's better for a child to be with a loving family than in an institution. Obviously trans-racial and trans-cultural families face challenges. But the most important thing is that children have parents. Period."

Mother Tongue is at the Edinburgh Festival Fringe, at Summerhall, from August 4