Tim complains about yet more research on the gender pay gap. But here's a queer thing. The same issue of Centrepiece reports on the pay gap between lesbians and heterosexual women.
And guess what? Controlling for obvious things like education and occupation, lesbians earn 11% more than heterosexual women. Most of the male-female pay gap, then, is a penalty for heterosexual women only, not for women in general.
There are four possible reasons for this:
1. Heterosexual women suffer a pay penalty because of the risk they'll leave to have children. Lesbians suffer this less.
2. Selection bias. The sort of people who admit to being lesbians in a survey are likely to be more than averagely confident. This could raise their pay.
3. The pay penalty that women suffer is a penalty for psychological gender rather than physical gender. There's some academic evidence (not just old jokes) that some lesbians have more masculine psychological traits than straight women, as measured by (say) the Bem Sex Role Inventory. If it's masculine psychology, rather than male physicality, that gets a pay premium, this would benefit some lesbians.
This, though, is a mixed blessing. Other research has found that masculine psychology is a drawback when investing (pdf).
4. Maybe lesbians have unobserved characteristics that make them attractive to employers. Perhaps the fact that growing up knowing they are in a minority makes lesbians more adaptable or creative. Certainly, there's strong evidence that some are geniuses.