When it comes to sexism, it’s hard to argue with data. The gender pay gap is one of the most blatant and consistent indicators of inequality between men and women.

In Ireland, the gap is widening, up from 13.9 per cent to 14.4 per cent in recent years. We’re so used to the gender pay gap that it almost feels like an unmovable constant.

People study it, report on it, gather stats on it, but it’s still there. There is nowhere near as much research done on the so-called lesbian wage premium, but an increasing number of studies could provide some insight into how women as a whole might close the gap.

Studies are showing that lesbians earn more than straight women. The data varies widely depending on where the research is done.

A 2009 study in the US put gay women’s earnings at 6 per cent more that straight women when all other factors were taken into account.

“Sexual Identity, Earnings, and Labour Market Dynamics”, a study published in April that focused on Australian data, found lesbians make at least 33 per cent more than heterosexual women.

That study also found lesbians work about 20 per cent more hours than straight women.

More and more studies are cropping up coming at the issue from a variety of angles, but the ability of lesbians to out-earn straight women remains the same.

Why? And if we find out why, what can straight women learn from gay women’s earning prowess?

Do lesbians hold the answers to tightening the gender pay gap? As a general rule then, straight men earn the most, followed by gay men, then lesbians, then straight women.

What the data tells us over and over, is that straight women are at the bottom of the pile when it comes to earning power.

Logic should dictate that lesbians are at a double disadvantage for being both female and gay, and should therefore earn the least of all adult demographics – but they don’t.

The pink pound is a myth, but maybe the sapphic shekel has something going for it. (That same Australian study found that gay men are earning a remarkable 20 per cent less than straight men.)

Straight men benefit financially from being in a couple – a marriage dividend.

Yet for many women, marriage and childrearing have massive consequences for their own earning power.

The sexist expectation that a man will always earn more than a woman in a couple might even preemptively damage a woman’s earning power. Not so for lesbians.

A Canadian study this year titled Gay Pay For Straight Work, found that while gay men with partners earn about 5 per cent less than straight men with partners, lesbian women with partners earn about 8 per cent more than straight women with partners.

Maybe it’s not marriage that impacts negatively on a woman’s earning power; maybe it’s heterosexual marriage.

You might think the reason for lesbians earning more is obvious: they are less likely to drop out of the workforce to have children, therefore their careers aren’t interrupted, and they earn more as a result.

Maybe, then, the lesbian wage premium will begin to fade as more gay women have more children.

But here’s an odd thing: a paper by the University of Massachusetts Amherst (2013) titled Motherhood and the Lesbian Wage Premium found that while motherhood “typically negatively correlated with wages for straight women, it is positively related to wages for the group of lesbians as a whole”.

As a whole, lesbians’ wages don’t suffer when children come into the mix. Maybe it’s not motherhood punishing women’s earning power; maybe it’s heterosexual motherhood.

Do lesbians earn more because of the types of jobs they have? A study of first-time job seekers in the UK published in April of this year, showed that gay people of both sexes are discriminated against when it comes to job applications (5 per cent less likely to be offered an interview than heterosexual applicants.)

Job interviews

Lesbians receive the fewest invitations for interviews in traditionally female-dominated occupations. Maybe this discrimination inadvertently guides gay women towards more male-dominated industries, and therefore higher-paid ones. Vice versa for gay men.

Perhaps there are much more subtle reasons that could be both controversial and harder to get data on.

Maybe sexist dynamics within heterosexual couples cause straight women to slip down the earning scale.

Lesbians will never view their career as second fiddle to a male partner’s because they don’t have male partners.

The burden of childcare in a lesbian relationship won’t just be placed on “the mother”, because there are two.

Would a prospective employer be less likely to discriminate against a gay woman in terms of progressing her career considering they might assume she won’t leave the workforce?

Do lesbians simply “lean in” more, ignoring the traditional subordinate roles women have taken in the workforce?

Do they ignore the heterosexual politics of workplaces, negotiating raises without caring about what male bosses think, or do male bosses in turn see them as “one of the lads” with all the financial benefits that might have?

It’s easy to fall into stereotyping, but there could be something in it. Regardless, lesbians don’t hold all the economic answers, because one main discrimination remains: the female gender.