The Mail on Sunday can today unmask an anonymous sperm donor who boasts that an astonishing 32 women are expecting his babies and another 15 are about to take pregnancy tests after asking him for donations.

Declan Rooney, 42, claims he is ‘Britain’s most successful sperm donor’ and says he has donated sperm to two more women who have already given birth.

He also has six children born naturally with three different mothers – meaning he has the potential to be the father of 55 children.

The former web designer runs his website under the alias Upton North and advertises himself on Facebook to single women, lesbians and couples desperate for a baby.

Last night experts called for an investigation into the unregulated and potentially dangerous service he provides to women he meets online, with one sociologist saying that Mr Rooney was ‘determinedly engineering a one-man eugenics movement’.

Medical experts fear he could create a ‘ticking timebomb’ by flouting official guidelines for sperm donation, which limit the number of families that legitimate sperm donors can help create to a maximum of ten.

As well as growing up without knowing their father, his children will potentially live close to each other, meaning that half-brothers and sisters may meet and unwittingly have children of their own.

The murky world of unregulated sperm donation has come under increasing scrutiny from watchdogs as the internet offers men and women easy opportunities to meet up anonymously and create families – without needing to qualify or pay for expensive private fertility treatment, overseen by doctors. A cycle of artificial insemination costs £850 privately and is only offered to selected patients on the NHS.

Rooney set up his anonymous site last March, offering to visit women in their homes or hotel within a 50-mile radius of his Middlesbrough home and give them a sample of his sperm in a specimen pot for them to inseminate themselves.

His website, which was taken down last night after he was contacted by The Mail on Sunday, stated: ‘I am willing to help either through artificial insemination or naturally with no strings attached.’ Despite that wording, he told this newspaper that he does not have sex with the women.

Sperm donations are not illegal unless a man charges for the service, but the risks of private donations include reports of women being abused, pressured into sex or forced to hand over money when they meet a donor.

Rooney, who insists he acts within the law, says he only charges ‘expenses’ and that his motives are purely ‘altruistic’. He said: ‘I like helping people’. And he added: ‘Have you changed anyone’s lives for the better?’

Since becoming a sperm donor, Rooney says two lesbian women in the North East have given birth to his children. He said: ‘When I was told, I was really happy for the mothers. I like meeting new people, I like hearing their stories, I like problem-solving. I’m quite an altruistic person. I haven’t done anything illegal.

‘I set myself up as a private donor and have been inundated – I have 5,000 emails. If they are too far out of the area I say no to them. If you say you’re a sperm donor, people say it’s really smutty, but if someone said they were an egg donor it’s like “Wow that’s amazing”. There were a few days when I had a success each day. It’s a good feeling.’

On Rooney’s webpage he backed up his claims by posting photos of ultrasounds scans, positive reviews from female recipients and an image of a specimen pot.

A HUMAN Fertilisation and Embryology Authority (HFEA) spokesman said: ‘Unfortunately, women finding a sperm donor online, rather than through a licensed clinic, run a number of risks. Apart from the personal safety risks to the woman, the donor won’t have been screened for infectious diseases like HIV, or for inherited illnesses, and he will probably also be the legal parent of any child that is born.'

Dr Suvir Venkataraman of London’s Harley Street Fertility Clinic, added: ‘A registered clinic will inform a child of a donor who else has been born using their sperm so they don’t have a sexual relationship with someone sharing the same genes. This man cannot expect to keep tabs on everyone and that is a big risk.’

Mr Rooney, who says his partner ‘understands my reasons for donating’, claims that his family have had no medical issues in five generations. ‘I wouldn’t donate if I had something genetically wrong. And there is no risk that my offspring will unknowingly have sex with each other because evolution makes sure that we are not attracted to people with the same genes,’ he claimed.

He also boasted that he is ‘immune’ from the Child Support Agency. ‘The CSA has to find your taxable income and assets. They would have difficulty. I’m not scared of them,’ he said.

Mr Rooney was photographed on the front page of the Daily Mail in 1993 leaving court smirking after he was found guilty of causing £60,000 of graffiti damage. He was given a suspended sentence and served seven months in a young offenders’ institution while waiting to stand trial. As he stepped out of the dock he said: ‘My barrister’s a genius. I’m laughing. It’s a soft touch.’

Questioned on his criminal past last night, he said: ‘I don’t mention it to recipients, but if the subject comes up then I will talk about it.’

Sociologist Claire McQuoid has researched private sperm donation and is setting up a charity for women who have been abused by donors. She said: ‘When Upton North appeared on the scene he developed a reputation for someone determined to impregnate as many women as possible, with no concern for child welfare, or indeed the women themselves. His aggressive online marketing is akin to a eugenics mission where he competes with other donors.’

Source: Ellery B., Taylort J. (2015) “Unmasked: Sperm dono