Some men were motivated by altruism, by how their simple act could bring a lifetime of joy to a childless couple. Others were keen for a quick buck — the going rate back then was $10 per cup of healthy semen.

Whatever made them do it, thousands of Australian men did, secure in the knowledge they would remain completely anonymous.

“It was out of sight, out of mind,” donor Ian Smith told news.com.au

“We got the strong sense that we would forget this and I think the doctors were keen that we didn’t think too much about the fact we were actually creating babies.”

Mr Smith was single and in his early thirties when he donated, out of altruism, at Melbourne’s Prince Henry’s Hospital (now Monash Medical Centre) in the late 1980s. He never questioned it, he said. His life carried on, he had two children of his own, and thought little of his donor past.

That is, until about 15 years later, when a letter from Monash IVF revealed he was the father of seven donor-conceived children.

And it finally struck him.

“That was the point at which I realised the enormity of what I had done — that there were seven other people out there who were as much genetically my children as the children who grew up with me,” he said. “It was quite a profound realisation.”

Mr Smith had donated under strict anonymity, but this revelation changed his attitude. He is now open to being approached by his donor-conceived children, and has been fighting for their right to do so.

Mr Smith is soon to appear in a new documentary, Sperm Donors Anonymous, airing on the ABC next month, which looks at the effects of anonymous sperm donation on donors, donor-conceived children and their families.

For years, Mr Smith’s was one of voices calling for changes to Victorian laws that would allow donor-conceived people to know the identity of their anonymous egg or sperm donors.

Mr Smith spoke at a Victorian parliamentary inquiry into donor conception in 2012.

The Victorian government is now considering the changes, which were outlined in a discussion paper handed down last month.

The proposed changes would bring the rights of donor-conceived children into line with the current law, which only allows those children born after 1998 full access to their donor’s personal information.

There are also calls for a privacy surrounding donor conceptions national approach to strip away the.

While many believe the move is unfair to those who provided sperm anonymously, Mr Smith says donor-conceived children have a right to know about the unknown half of their DNA. Especially when it comes to providing crucial information about their family’s medical history.

“We’ve got a problem here when you’ve got donors like me who were promised anonymity, you’ve got donor-conceived people who are saying they’ve got a human right to know about their heritage and ancestry, and at some point one of those sets of claims has to give way,” he said.

“I know donors who say the opposite, who say, ‘No, we were promised anonymity and it’s not OK to remove it’, and I can understand where they’re coming from. For some of them, after 40 years, to suddenly turn that around is a big thing.

“As complicated as it may be for my family — and it will be, if I ever meet any of my donor offspring — I’m resolutely of the view that the donor-conceived people, who want to have that information, have a fundamental right to that information.”

Mr Smith thinks more donor dads would be keen to hear from their children than we might think.

There is a voluntary register in Victoria that can facilitate the exchange of information between donor parents and children, and Mr Smith says the number of donors registered outweighs the number of donor-conceived children two to one.

Mr Smith came close to meeting one of his donor-conceived offspring once. The youngest, a 17-year-old girl, got in touch through the voluntary registry.

“We shared first names, and she asked me information about my medical history so I supplied that,” he said.

“That’s the last I heard from her. She’s a young woman, she’d be in her early 20s now and it’s up to her to make contact. I made that clear in the letter that I wrote to her.

“That might have satisfied her need to know, and as much as I’d really love to meet her and any of the others, I’m also very respectful that it’s their decision.”

Of the tens of thousands of donor-conceived people in Australia, some aren’t motivated to contact their donor parents. Some don’t yet know they were donor-conceived — some yet might never know.

But many have spoken of the anguish of not knowing who their fathers are and the frustration of not being able to find out.

Mr Smith said it’s tough for the donors, too.

“It is a big emotional impact,” he said.

“A lot of the commentary and discussion focuses on the donor-conceived people but I think it’s equally important to look at the impact on donors and it varies.

“I would really love to meet (my donor-conceived children), even once, because they are my children. There’s that emotional turmoil. Equally there are those donors for whom the emotional turmoil, in extreme cases, is fear. It’s, ‘Oh, wow — this is something I did 30, 40 years ago and now I have this complexity in my life and I have to work through it’.”

Mr Smith said being a donor was an isolating experience. He helped form MADMEN (Melbourne Anonymous Donors), a group providing information and support to donor dads.

“Donors seem to be the ones who are in the shadows,” Mr Smith said.

“What was really striking at the time (of forming MADMEN) is when you meet new people in the group, they say, ‘I’ve never talked to anyone who gets this and understands this’.”

‘NOW I’M A GRANDFATHER’

Michael Linden knows what it’s like to meet donor-conceived offspring — he’s met two of his.

In 2001, he read a newspaper article about a girl looking for her biological father. One glance of the photo of the girl, named Myf, was enough to convince him he was her dad.

The two made contact, and through Myf, Linden met her brother — his biological son — Michael. Linden says he’s as close with the pair as any of the children he raised from birth.

“Going over my first meeting with Myf sends tingles up my spine,” Mr Linden said.

“When Myf sent her first little note, she was like, ‘I’m left-handed, I’m really artistic, I’ve got blonde hair and blue eyes’ and I was like, wow. She was vegetarian at the time, as I am. We were almost a perfect match.

“When I met Mickey, it was like the complete opposite. His social father’s this blokey bloke. I’m not a blokey bloke. Mickey had a lot of influence from him. But then I realised Mickey’s a really sensitive guy as well, and when he met me and my wife ... he kind of softened up and got into all this esoteric stuff. He even started growing his hair long.”

Mr Linden became a donor — partly out of altruism, partly for some fast cash — at the Royal Women’s Hospital in Melbourne in 1977.

Like Mr Smith, Mr Linden didn’t really consider the implications of it. Neither did the clinic.

“It wasn’t sufficient,” he said. “They were hardly, or not at all, informing us of the implications of what we were doing. They were more interested in checking us out medically and getting the goods.”

From what he provided during that visit, Mr Linden also fathered three more children — his “missing daughters” — none of whom he knows.

He has vague, non-identifying information about them — their parents’ occupations and the general area they lived.

While Mr Smith thinks the proposed changes to the donor conception laws go far enough, Mr Linden argues they should go much further. He says donors should be legally allowed to contact their offspring, not just the other way around. He wants the chance to contact those missing daughters.

“It seems so out of step with adoption legislation that went back to the late 1980s,” he said. “People who have their children up for adoption are allowed to seek their children and it’s always been an inequitable issue when it comes to donor conception. It’s not different, on the part of the donors it’s got the same feeling of really wanting to connect with those children.”

He suspects his three unknown daughters probably haven’t been told they were donor-conceived, and he thinks it’s wrong to keep donor-conceived children in the dark.

“I feel it’s this cowardice,” Mr Linden said. “I can’t believe you would raise a child and hold that information from them. It’s such a fundamental lie. Who are you protecting, yourself or them? Or you don’t want this mystery man to come into their lives?

“They’re (the children) are living entire childhoods with this niggling feeling that they don’t fit in or there’s something missing.”

Through making contact, Mr Linden has not only formed a bond with Myf and Michael, but he’s become a grandfather too, through Myf’s two children.

“I’m seeing those grandchildren grow up and it’s kind of a next-generation thing happening when I'm part of that life, from birth, where I wasn’t part of Michael and Myf’s life from their births,” he said. “I’ve got this chance to see that cycle as a grandfather.”

As with Mr Smith, Mr Linden will appear in the documentary, Sperm Donors Anonymous. It will share the experiences of a number of donors and donor-conceived children, including Myf Cummerford, as well the perspective of Myf’s social dad, Simon.

“It’s really quite moving to get that perspective from him as that hasn’t been seen before,” Mr Linden said.

Ian Smith said he hoped the documentary would empower and inspire people on all sides of donor conception.

“My hope is that it will help men who have been donors and are thinking of the implications and the repercussions for them,” he said.

“I hope it will help parents of donor-conceived people, particularly if they have not told their children of their conception, and that they’ll see we’re not frightening people, we’re not there to steal their families away from them. And for other donor-conceived people who know about the basis of their conception and are wondering whether to make contact. I hope the documentary will encourage them to ask that question.

“It’s about removing this shadowy figure of the donor and giving a voice to that.”

Sperm Donors Anonymous airs Tuesday, August 18 at 9.20pm on the ABC.