A couple have revealed how their 20-year-old son, who died last year, secretly fathered two children with his aunt's lesbian lover.
Charlie Lowden entered into a pact to help his aunt Sarah and her partner Claire have a family of their own.
The details of the arrangement would have remained secret if the young scaffolder hadn't died following routine surgery just before Christmas last year.
Lasting gift: Charlie Lowden (left) donated sperm to his aunt, Sarah Ashman (above, left) and her partner, Claire, who gave birth to Carlton and Sarah
Charles and Lynn Lowden's lives were shattered when Charlie died.
But they have drawn comfort from the discovery that the boy and girl they thought were niece and nephew are, in fact, their grandchildren.
Surprise: Lynn and Charles Lowden never knew that their son had fathered Sarah and Claire's two children
Charlie had secretly donated sperm to help his mum Lynn's sister, Sarah Ashman, and her partner Claire.
Claire, 30, later gave birth to Carlton, now five, and Sarah, two.
They kept the secret of their children's parenthood between themselves until Charlie's death inspired Sarah to make an emotional confession to her sister.
Charles and Lynn, from Bedlington, in Northumberland, were stunned by the news at first.
But their shock on discovering the youngsters had been conceived with their son's help turned to joy as they recognised he had left them with two grandchildren to treasure.
Speaking for the first time since learning she was a grandmother, Lynn, 52, paid tribute to her son.
Three generations: Lynn Lowden is pictured with her other children Jonny and Ruth, sister Sarah Ashman, Sarah's partner Clair, and their two children Carlton and Sarah
'When our Charlie died we were broken hearted. We thought we had nothing left of him. But there is something left of him,' she said.
'I just wish that we had known about all of this before he died so that Charlie could have known we had accepted it.
'When Charlie died, Sarah said I had no idea how special he had been to her, but now I do. And I wish he was still here to see them both.
'Carlton is the spitting double of him. They are so much alike. He is built like him, talks like him and even has a freckle on his ear like him. But I just didn't click.
'My husband Charles was suspicious, but I didn't think anything at all. I used to look after Carlton every Wednesday when he was a baby and Charlie would run in from work, pick him up and hold him up to the mirror and say "Who's the daddy? I'm the daddy" and I still didn't click.
Proud dad: Charlie loved playing with Carlton
'But it's just like having our Charlie back. We've got the next best thing to him and it's not a secret anymore. I'm absolutely delighted. He did it for a reason and he has left a legacy. He is such a big miss.'
Sarah, 40, and Claire, of Choppington, Northumberland, who have been partners for 14 years, tied the knot in a civil ceremony in July last year.
The couple had been desperate to start a family, but were left devastated when beautician Claire suffered a miscarriage after falling pregnant by another donor seven years ago. Charlie, 16 at the time, then volunteered to help.
Sarah said: 'Charlie was very special to me. He was great. When he died, it was our secret. But I had to tell my sister. I couldn't go through life not telling her, because they are her grandchildren.
'Lynn had been so upset. She said she hadn't anything left of Charles and we decided to tell her.
'He was such a lovely lad and I'll never ever forget what he did for us. He gave us a family. He was so special. I would give him the world if I could.
'After Carlton was born, Charlie said he would help us again if we wanted another child. He used to say 'if you need me, you know where I am'. So that's what we decided to do.
'We used to do everything together and I think that's why he came to me. He approached me and said that nobody would think any different.
'He was so proud when Carlton was born. He used to go on about teaching him how to play football when he got older, but he's not going to be able to do that now.
'They both know who their father is and they ask for him all of the time. He used to take them to the park and we would have Sunday lunch together.'
Charlie died on December 9 last year after he suffered severe chest pains and began vomiting blood just days after a hernia operation at Hexham General Hospital. His parents are taking legal action.
Sarah added:'His death has totally broken all of us. It's just shattered the whole family.'
