Slogans on T-shirts have been causing controversy for as long as the T-shirt has existed. So it's not surprising that a picture of a young boy in a shirt bearing the slogan "My daddy's name is Donor", which appeared in the Chicago Tribune two years ago, should have so offended Elizabeth Marquardt, of the Institute for American Values, that she felt compelled to write a book bearing the same title.

"What troubles me is that children today are being raised in an era of increasingly flexible definitions of parenthood," she says. "Definitions that often serve the interests of adults without regard for children."

Marquardt challenges the assumption that advances in reproductive technologies are an unequivocally good thing, arguing that debates about methods take into account only the wishes of the parents, not the children.

Marquardt has solicited the views of donor children from across the world. These "babies" are now grown up (one of the most vocal voices is pushing 70) and many are very unhappy.

"They tell me that their early attempts to make sense of their origins were made more painful by the people around them who insisted that it shouldn't matter," Marquardt reports.

Marquardt is prepared to concede that the donor offspring she has spoken to may not be representative of the group. "It is possible that the young people most troubled are the ones who reach out to others." She therefore plans to embark on a representative study involving 900 individuals and a control group to measure attitudes among the donor offspring community.

Olivia Montuschi, of the UK based Donor Conception Network (DCN), believes that the results of such a study will force Marquardt to eat her words. Montuschi is frustrated that Marquardt is speaking out so vocally before collating the evidence.

Montuschi and her husband conceived their two children using donor sperm in the mid-80s and were in the vanguard of parents who decided to be open with their children, despite the advice being given by the medical profession.

"We believed that our children had the right to be told," says Montuschi. "In my experience, donor-conceived adults and young people who feel angry are those who found out late and in less-than-ideal circumstances -- during a row, a medical emergency, or following bereavement."

A study by Dr Susan Golombok published in the journal Human Reproduction in 2006 reported that 54 pc of UK parents who had used donor sperm had opted for disclosure, but the situation in Ireland is very different.

Mary McNeamey, manager of the Morehampton Clinic; who introduced sperm donation to Ireland back in 1979, says that there was, then, a huge taboo around the subject. It is unlikely, she says, that any offspring will be aware of their status. 'Today there are approximately 200-250 pregnancies a year through donor sperm in Ireland," she says. "Five clinics now provide the service. But we believe that 95 pc of couples never tell their children.

"Parents here still feel it is better if it not discussed. They still want their child to believe he is genetically theirs."

The Morehampton Clinic uses sperm donors from Denmark. Donors have complete anonymity, and McNeamey believes the children will never be able to trace their biological parents. "That is one reason that parents are unwilling to tell their children," she says. "They cannot learn any more. You are telling them something but are unable to fill in the details."

Anonymity was lifted in England back in 2005. There, a child can seek identifying information once he or she reaches 18. A recent study there, involving 16 families who had disclosed, showed that the children were comfortable about their identity and enjoyed positive relationships with both parents.

According to Helen Brown of NISIG -- a support group for couples battling with infertility -- parents don't worry too much about the issue of donation while they are going through the process.

"The main issue is to get pregnant," she says. "The impact of donor sperm or eggs only occurs to them afterwards. Quite a few of our members are, now, telling their children that they were born through donor sperm, or eggs."

In England, couples are counselled. And it worries Brown, that there is little support for Irish families.

"At NISIG we have a donor line, manned by a mother who has been through the experience herself," says Brown, "but there is no other back up for them. Parents need guidance on telling children; and on managing their worries about their identity."

Mary McNeamey thinks that if a parent is going to tell, they should do so early. But Christine Whipp, of the action group Tangled Webs, which challenges donor conception practices, believes that if told early, donor offspring can be "brainwashed by their parents into believing that they have not been short-changed, but biological relationships do matter".

Tangled Webs claims that donor conception practices contravene the UN Convention on the Rights of the Child. It wants future legislation to provide offspring with retrospective access to information about their biological/genealogical parentage.

So, does the T-shirt slogan express the voice of the donor child, or is it wishful thinking by parents who seek to dismiss donor origins as no big deal? Elizabeth Marquardt believes it is the latter.

"We cannot assume that donor offspring easily forget about their biological parents just because the adults in their lives want them to. Our culture needs a serious debate about the implications of technologies used to form many of today's alternative families, one that places the interests of the resulting children front and centre."

'I felt like a sordid secret transaction'

Christine Whipp, 52, received a letter from her estranged mother 10 years ago telling her that she had been conceived using donor sperm.

"I had guessed that there was some big secret around my identity but it was a complete surprise -- I hadn't even been aware that donor conception was available in the 1950s. But it made sense. I had always felt that my mother viewed me as second best -- not the baby she really wanted. When she looked at me she saw a stranger and it affected our relationship until she died.

"At 41, I had to reassess my life. I felt like a sordid secret transaction, something my mother would have been ashamed of. I mourn that I didn't have the chance to grow up knowing my real father. It took me nine years to trace him, by which time he was dead.

"Now I have regular contact with one of his sons and that has been incredibly reaffirming but nothing can make up for the years that I have lost. Reproductive technologies are viewed as a success if a bouncing baby is produced, but that is no guarantee of a happy-ever-after."

I know that 'daddy' mean love, not sperm

Susannah Derricks, 21, was conceived using a donor. Her parents were open with her from the outset.

"I don't remember when I was told that I was donor-conceived. The information was just always around and I accepted it as normal. It was always an open subject: I could ask questions. Consequently, it has not been a big issue.

"If I had found out by accident it would have been very different and I know it would have damaged my relationship with my parents. I really respect them for letting go of their own feelings and focusing on the needs of their children and our right to know.

"If parents hide the truth it seems to imply that it is something to be ashamed of. I never felt ashamed and have always been happy to tell people if the topic arises. It actually made me feel special and interesting. I liked being different.

"There has never been a question about who my father is: a father is someone who loves and raises you. I have always known that 'daddy' means love and not sperm. I respect my dad for being able to face up to his infertility.

"I am registered on UK DonorLink and would be interested in information about my biological father, but I don't spend a great deal of time thinking about it. I believe that it would be a waste of energy.

"Donor insemination is important, because it's about half of my genetic background, and yet it's not important at all."

- Catherine Bruton