As a femme in a culture that denigrates femininity, a bisexual in a queer movement still uncertain about the B in LGBT, and a transgender person among feminists who still frequently mistrust trans women, Julia Serano has a unique perspective on feminist and queer issues. Perhaps what most sets her apart from other writers on these topics, though, is her profession. Feminist and queer theory is almost entirely the province of humanities scholars; Serano is a biologist. As such, she has an unusually nuanced view on the question of nature vs. nurture, a binary she characterizes as “completely ridiculous.”

Serano rejects the idea that gender is a performance, or a social construction, or a biologically determined truth. Instead, she argues, gender and sexuality are complex traits, in which biology, social norms, and individual choice interact in ways that can’t be either teased apart or reproduced. We don’t understand why people are the gender or sexuality they are, so there’s no grounds on which to judge them for it. Feminine lesbians aren’t worse than butch lesbians; bi people aren’t worse than gay men or lesbians; asexuals aren’t worse than kinksters; and women aren’t worse than men. People are just different.

If gender and sexuality are different for everyone, it makes sense to conceive of sexism in more individual terms as well—which is what Serano (Whipping Girl: A Transsexual Woman on Sexism and the Scapegoating of Femininity) does in her new book, Excluded: Making Feminist and Queer Movements More Inclusive. Rather than thinking about oppression in terms of a single coordinated system like patriarchy or heteronormativity, Serano argues we should think about it in terms of a series of double standards that single out different people in similar ways. Women are prudes if they dress conservatively, and sluts if they don’t. Trans women in feminist spaces are seen as parodying femininity if they’re too feminine, and as inescapably and malevolently masculine if they aren’t feminine enough. These kinds of double binds are used to denigrate and discriminate, in society as a whole as well as within activist and marginalized groups. It’s not a single system we need to get rid of, Serano argues—it’s all double standards, everywhere.

There are limits to this approach, as Serano acknowledges. Sexism isn’t just individual, after all—it’s also systematic, which is why concepts like “patriarchy” are important. Nonetheless, Serano’s ability to show the structural links between different forms of discrimination is eye-opening. Her new book is a must-read for anyone interested in equality, or just in treating each other more decently.