Emotive arguments and questionable rhetoric often characterise debates over same-sex marriage. But few attempts have been made to dispassionately dissect the issue from an academic, science-based perspective.

Regardless of which side of the fence you fall on, the more robust, rigorous and reliable information that is publicly available, the better.

There are considerable mental health and wellbeing benefits conferred on those in the fortunate position of being able to marry legally. And there are associated deleterious impacts of being denied this opportunity.

Although it would be irresponsible to suggest the research is unanimous, the majority is either noncommittal (unclear conclusions) or demonstrates the benefits of same-sex marriage.

Further reading: Conservatives prevail to hold back the tide on same-sex marriage

What does the research say?

Widescale research suggests that members of the LGBTQ community generally experience worse mental health outcomes than their heterosexual counterparts. This is possibly due to the stigmatisation they receive.

The mental health benefits of marriage generally are well-documented. In 2009, the American Medical Association officially recognised that excluding sexual minorities from marriage was significantly contributing to the overall poor health among same-sex households compared to heterosexual households.

Converging lines of evidence also suggest that sexual orientation stigma and discrimination are at least associated with increased psychological distress and a generally decreased quality of life among lesbians and gay men.

A US study that surveyed more than 36,000 people aged 18-70 found lesbian, gay and bisexual individuals were far less psychologically distressed if they were in a legally recognised same-sex marriage than if they were not. Married heterosexuals were less distressed than either of these groups.

So, it would seem that being in a legally recognised same-sex marriage can at least partly overcome the substantial health disparity between heterosexual and lesbian, gay, and bisexual persons.

The authors concluded by urging other researchers to consider same-sex marriage as a public health issue.

A review of the research examining the impact of marriage denial on the health and wellbeing of gay men and lesbians conceded that marriage equality is a profoundly complex and nuanced issue. But, it argued that depriving lesbians and gay men the tangible (and intangible) benefits of marriage is not only an act of discrimination – it also:

disadvantages them by restricting their citizenship;

hinders their mental health, wellbeing, and social mobility; and

generally disenfranchises them from various cultural, legal, economic and political aspects of their lives.

Of further concern is research finding that in comparison to lesbian, gay and bisexual respondents living in areas where gay marriage was allowed, living in areas where it was banned was associated with significantly higher rates of:

mood disorders (36% higher);

psychiatric comorbidity – that is, multiple mental health conditions (36% higher); and

anxiety disorders (248% higher).

But what about the kids?

Opponents of same-sex marriage often argue that children raised in same-sex households perform worse on a variety of life outcome measures when compared to those raised in a heterosexual household. There is some merit to this argument.

In terms of education and general measures of success, the literature isn’t entirely unanimous. However, most studies have found that on these metrics there is no difference between children raised by same-sex or opposite-sex parents.

In 2005, the American Psychological Association released a brief reviewing research on same-sex parenting. It unambiguously summed up its stance on the issue of whether or not same-sex parenting negatively impacts children:

Not a single study has found children of lesbian or gay parents to be disadvantaged in any significant respect relative to children of heterosexual parents.

Further reading: Same-sex couples and their children: what does the evidence tell us?

Drawing conclusions

Same-sex marriage has already been legalised in 23 countries around the world, inhabited by more than 760 million people.

Despite the above studies positively linking marriage with wellbeing, it may be premature to definitively assert causality.

But overall, the evidence is fairly clear. Same-sex marriage leads to a host of social and even public health benefits, including a range of advantages for mental health and wellbeing. The benefits accrue to society as a whole, whether you are in a same-sex relationship or not.

As the body of research in support of same-sex marriage continues to grow, the case in favour of it becomes stronger.