The fathers included Tom, the third child of Ginette and husband Terry, owner of the Canberra Airport, who had told them years earlier when aged 19 that he was gay.

Mrs Snow had guessed his sexuality, but recalls saying: ''Look, I'm really happy if you're happy, but you will miss out on something that I think is the most important thing in life and that's having a family.''

But Tom and his long-term partner Brooke Horne were determined to have a family and went to the United States to find a surrogate mother.

Now the Snows couldn't be happier.

Mr Snow said he had two choices - either accept a much-loved son as being gay or alienate him.

''It has been a great thing for me, and Tom is happy. He has these two wonderful children which I am delighted about, and he has a wonderful partner. You can't ask for more.''

Mrs Snow said the idea of her documentary, which opens with the Head On Photo Festival in St Peters, Sydney, next week, came when twin boy and girl Angus and Sybilla, now aged one, were born through surrogacy in the United States.

At 5.30am that day she had overheard Australian voices in the surrogacy ward while waiting for news of Tom and Brooke's babies, and turned to the two men saying: ''You wouldn't be a couple of gay guys waiting for some babies would you?''

They said yes and she photographed them later in Brisbane with their twins, and 22 other families for her first solo exhibition. ''I just love going to meet these families,'' Mrs Snow said.

''It is such a privilege to meet the parents and the kids. These parents are the same sex but that's where the differences end, they still face the same issues as other parents, such as balancing parenthood and work.''

Mrs Snow had spent an Easter holiday with the surrogate mother of her grandchildren, who had told her she loved her role and her husband had been supportive, even though she was pregnant with someone else's children. A mother of four and grandmother of 12, Mrs Snow has photographed gay and lesbian families from Sydney, Melbourne, Brisbane and Canberra and also in rural NSW.

''This is something that comes from my heart. I have grandchildren who have gay parents, therefore I don't want them treated differently to everybody else in the class.

''Anything I can do, even if it's just a little, small thing to make people accept their families, then I am happy.''

Tom, who moved from Canberra to Sydney in 2008, and Mr Horne are engaged and will probably marry overseas, where it is legal.

They struggle to understand the government's reluctance to accept gay marriage.