IF WE can't even decide whether vitamin supplements are good for our children - judging by one report last week by Copenhagen University Hospital in Denmark - we can forget about relying on the raft of studies since the 1970s about same-sex parenting, despite the fact that the resulting data is overwhelmingly supportive.
Social science, religion, law and politics are colliding with dangerous results, even though nearly 40 years of studies on children of gay parents predominantly conclude it's the quality of care that counts.
As we saw by last week's inadequate High Court ruling on the "de facto" family of a lesbian couple and child, to the exclusion of the rights of the biological father against his will, the issue won't go away. It is crying out for legislation. I agree with Breda O'Brien on one salient issue: "As the most vulnerable party, the rights and needs of the child must come first." (We differ quite a bit after that.) Children in all relationships - same-sex or opposite-sex - should be respected and dignified with adoption law that protects them.
Last month, Anna Sarkadi from the Department of Women's and Children's Health, Uppsala University, Sweden, said Patricia Casey's conclusion of her research "is not valid" and "there is nothing whatsoever in our review that would justify the conclusion that same-sex parents cannot raise healthy children who do well". Last week, Melanie Verwoerd, executive director of Unicef Ireland, wrote to this newspaper to say that yet another reference by Casey was "incorrect and unacceptable". Their words, not mine.
Casey is a patron of a conservative web-based "institute" that has hitched its wagon to the issue, and a professor of psychiatry, but I believe hers was a genuine attempt to support her world view.
"There is a real danger that this debate is going to be led by emotion," she has said. "It must instead be led by reason and a calm consideration of the facts."
I agree. As does the American Academy of Pediatrics, American Psychological Association and American Psychiatric Association - and many more - which support same-sex parenting.
Still, some organisations and commentators are like blinded moths, forever fluttering around the inextinguishable flames of gay civil rights. Happily, the flames won't burn them. Nordic Bliss? Scandinavian Registered Partnerships and the Same-Sex Marriage Debate, a book by Darren Spedale, William Eskridge and Hans Ytterberg, says in the years after Denmark, Norway and Sweden introduced same-sex unions, the rates of heterosexual marriage went up, while the rate of heterosexual divorce went down.
The US is years ahead in the evolution of non-traditional families and a fertile ground for studies. Early samples have been small and, sometimes, skewed towards white/lesbian households, but over time methodologies have greatly improved and been very - some say unusually - consistent. Some aim to prove that all families are the same. All families are intrinsically different. And that's okay. As for stigma, bullying or self-esteem issues, you may need to look at intolerant, divisive forces outside the family for sources of that.
In 2001, American sociologists Judith Stacey and Timothy J Biblarz reviewed 21 studies of children of gay parents. They found almost no systematic differences with opposite sex parents. In 2006, Dr Stacey said: "I am deeply troubled by the ways in which Focus on the Family wilfully misrepresents my research on lesbian and gay parenthood to support their ideological opposition to homosexuality.
"This politically motivated distortion of social science contributes to serious harm to lesbian and gay parents, and their children."
Data from studies is twisted and used in dubious ping-pong matches by groups at opposite ends of the political/social spectrum. Similar controversies plague cancer research, which pits mainstream medicine against other forms of care; race and IQ, where the argument centres around genetics versus environment; diet - see vitamins A and B, above; climate change; and, last but not least, the great debate of our age, boxers or briefs. (There is no empirical conclusion on the latter - it depends who's wearing them.)
Ultimately, we are left with the raw data: families. The debate on parenting will start and end with the individual.
That is why so many couples stand tall and are prepared to be interviewed by the media, only to be turned into a soundbite on TV, feature article or sensational tabloid headline.
This is why they subject themselves to that. They know that speaking about their experience of same-sex family life publicly is a powerful way for people to understand why they - and their children - need protection under the law, too.
We can quote or misquote studies. We can criticise or laud them. We can make papier mache dolls' houses out of them. We can hide our true feelings about homosexuality behind them. The reality is that same-sex families are on the increase whether people like it or not. For those who oppose that, the battle is already lost.
We can staple our objections to data and nail them to a crossword in The Irish Timesif we want to. But the global winds of change are coming and, sooner or later, will blow those objections away.