OPENING my account on a DNA website, my heart suddenly started to race as I tried to make sense of the results in front of me.
I had a sibling I never knew existed, but she wasn’t from a secret family my dad had kept from me, and she wasn’t the product of an illicit affair either – the reason was something I would never have believed in a million years.

A DNA test revealed Rebecca Coxon had been conceived using a sperm donor Credit: Simon Wiffen

Rebecca grew up with three siblings (pictured when they were young) but later realised she had many more Credit: Supplied
The name on the screen was Lucy Hamilton and, according to 23andme.com, we shared 27.9 per cent DNA, making us half-sisters.
After wondering if she was a long-lost cousin, I contacted Lucy directly; her reply was quick.
“My father was a sperm donor”, she wrote. “Amazing to have a new blood relative.”
I was in shock – we had the same father, but it wasn’t the man who had raised me.

I had known since I was a teenager that my older brother Tim, 39, and my triplet siblings, Joe and Ruth and I had been born via IVF because my mum Sandra, 75, couldn’t conceive naturally and my dad John, also 75, was told his sperm wasn’t viable.
But I had no idea they had used a sperm donor – and that me, Joe and Ruth weren’t biologically related to our dad.
Despite their struggles, we had a lovely childhood growing up in Nottingham, and my dad was a huge part of that.
We lived near woodland, and my dad was a joiner, so he used to build treehouses for us. As kids, he would play with us for hours.

Rebecca had no reason to believe she wasn’t related to her dad Credit: Simon Wiffen – Commissioned by The Jattvibe Fabulous Magazine

Rebecca met up with half-siblings Lucy and Libby, who lived only eight minutes away Credit: Supplied
People have always said I look like my dad. I’ve never had reason to think we weren’t biologically related at all.
I knew that our dad had been adopted, which was why, in 2016, I signed up to 23andme.com ancestry site.
I thought I might find something interesting about my dad’s background.
At first, I didn’t find much: we had mainly British ancestry and I had a slight increase of getting dementia.

It wasn’t until three years later that I discovered Lucy was my half-sister.
At first I wondered if the IVF clinic had mixed up his sperm or if they’d used his sperm without his consent.
Either way, I knew I had to find out the truth.
I sent a screenshot of Lucy’s message explaining that her dad was a sperm donor to my mum and eventually asked the big question.

“Am I not related to Dad?”
She eventually texted back.
“Dad and I need time to digest the info … can we talk at the weekend?”
A few days later I travelled to Nottingham to see them, but when my mum picked me up from the station, the atmosphere was frosty.
When we got home at first they were hesitant to discuss it all, but then the truth came out – they had used a sperm donor.
My dad started crying – it was the second time I had ever seen him cry; the first was after my nana died 20 years previously.
My dad then asked: “Does it change anything?”
And I said: “No, it just proves how much you wanted us.”

Rebecca knew she was born via IVF as her mum (pictured with Tim) couldn’t conceive naturally Credit: Supplied

Rebecca and Libby went to Paris to meet Eliza, a half-sibling who lived in Russia, in 2024 Credit: Supplied

Nobody wants to upset their parents, and I had really upset my dad.
It was awful because it was due to something I had done.
I was so embarrassed and felt so guilty, as if I had ruined everything.
I felt ashamed that I had gone digging and uncovered something that could ruin my whole family.
My parents said we would have to tell my siblings, but I couldn’t bear to put my dad through more pain.
I suggested we keep it from them and put it to one side.
But that wasn’t the only secret.
Lucy – who was six months older than me – revealed she had a non-identical twin, Libby and, like me, they both worked in London.
In fact, Libby lived in Dalston, which was eight minutes away from me in Shoreditch.
I decided to meet up with both sisters, and two weeks later we arranged a date at a pub in London.

We could immediately see the resemblance between us.
It was overwhelming, but we got on amazingly well, and we all had the same sense of humour.

Rebecca says the half-siblings keep in touch and meet up when they can Credit: Supplied

Though Rebecca now has bonus people in her life, she says they haven’t replaced anyone Credit: Simon Wiffen
We formed a WhatsApp group and started meeting up once every few months, going out drinking and doing what normal people in their late 20s in London do.
However, I didn’t tell my parents because they were in enough pain, and I’d agreed not to tell my other siblings about their existence at all.
I felt like I was leading a double life.
Then in January 2020, my biological father – who went under the pseudonym Rodney – joined 23andme.com.
I found out he was in his early 20s and a chemistry student at Nottingham when he agreed to give his samples.
He had discovered three more half-siblings through the Human Fertilisation and Embryology Authority (HFEA).

There were twins who lived in Russia – Eliza and Mike – and Ben, who lived in the UK.
We all connected over Zoom – lockdown meant we couldn’t meet up in person – and created a WhatsApp group.
Even though I was enjoying getting to know my new half-siblings, I felt so guilty.
At the time, I had moved back into my parents’ house where my brother Joe was also living, so I was having Zoom calls with my half-siblings in secret.
It was like opening Pandora’s box – once it was all coming out, I didn’t feel like I could push it back in.
While I was getting to know my extended family, I chose not to speak to Rodney.
But then in March 2020, I decided to donate my eggs because I wanted to provide for another family who couldn’t have children like my parents, but I knew I needed a full medical background from Rodney.
Connecting with him was really complicated and messy because I had a conflict of feelings towards him – firstly, I felt like I was betraying my own dad.
I also felt resentment that he was my biological father, but gratitude for what he did for my parents.
Without him and what he did, my lovely, happy family wouldn’t exist.

But the secret of keeping what I knew from my siblings was starting to wear me out.
By chance, I stumbled upon an agony aunt responding to a question from a mum of donor-conceived children who asked if she should tell them.
The answer was a very strong yes. I knew that I needed to tell my siblings.
I wanted to do it without my parents.
My dad had been so upset when we had first spoken, so I wanted my siblings to hear the news without having to deal with my dad’s emotions as well as theirs.
It was Christmas 2022, and my siblings and I were going to Tim’s house in Wiltshire without our parents – I knew that was my chance.
“I’ve got something to tell you all,” I said to them.
“Don’t worry, nobody is dying.”
And then I told them everything I knew.
I was ready for anger, tears and disbelief.

I was expecting huge emotions.
Shock, devastation. But they were quiet as they took it in and then asked me if I was OK.
They said it must have been so hard on me to keep this a secret for all this time.
Tim asked if he had come from the same donor sperm, but Rodney had started donating after he was born.
It means genetically he’s our half-brother too.
In the days that followed, Joe, Ruth and I were due to go to our parents, and Tim came along too.
He wanted to be with our dad.
We decided we had to tell them everyone knew the truth, but when we arrived, my parents were so happy to see us all together that we didn’t want to spoil the moment.
It wasn’t until the following Easter that we eventually told them.
They were shocked, and my dad became incredibly upset again.

It was hard, but it was the right thing to have it all out in the open.
All of the half-siblings have now met and keep in touch, and we see each other when we can now.
I wrote a book about my experience of donor conception, and Eliza and Ben came to my book launch in March this year.
I have so many bonus people in my life now.
But they haven’t replaced anyone. I come from a really happy family. I have three siblings I’m really close to, and I have a fantastic mum and dad.
I probably feel closer to my dad than ever now because I know what he went through to have us.
‘Inconceivable: On the True Meaning of Family’ by Rebecca Coxon (Big Day, £20) is available now.