I always like a book that wakes me up, makes my brain move in new directions, and offers new paradigms for thinking theologically. This book, while incredibly dense and filled to its electronic gills with footnotes, does this. It reads a bit like a dissertation, meticulous in its presentation, but worth the effort.

The author highlights several things. First, it is important to acknowledgement and respect past church teaching, even though theological conclusions are always precipitated into their own cultural context. Second, ideas, though captive in that culture, can be useful for forming new conclusions. Third, it is equally important not to be bound by previous thinking. Fourth, it is urgent for today’s theologians to dive into the vast sea of modern science (particularly epigenetics) to expand the lens by which they understand and interpret God’s word.

Part I examines the historical development of theologies of sexual identity and sin. The author begins with the biblical story of original sin and its early theological interpretations, particularly the work of Augustine. He sees human beings as binary: simply man or woman. Sin is passed biologically to succeeding generations. Some of Augustine’s views are positive (those on marriage, desire, and the body, for example); but they are, to quote the author, “inadequate.”

There are centuries of literary lacunae about human origins and human sexuality. This begins to change in the mid-twentieth century, with the work of nascent feminist thinkers (Valerie Saiving, Ruth Benedict, and Margaret Mead). For the most part they, like Augustine, accept an inherent binary notion of man and women. Yet a small window begins to open, shedding a broader light on sexuality and gender, and the essential interface with biology and culture needed to do theology today.

Part II moves more deeply into modern scientific resources. Darwin is discussed in relationship to later thinkers and even some church teaching. He is, like Augustine before him, a product of his (Victorian) context. The author sees Darwin’s evolutionary theory as an important grounding for feminist work on creation, sin, the body, and the nature of sexual difference.

Moving back to the contemporary Catholic context, she offers a surprisingly respectful discussion of John Paul II’s theology of the body and its intersection with contemporary Catholic feminists. Predictably, John Paul does not question the binary nature of human sexuality, following past church pronouncements. The author quotes biologist Anne Fausto-Sterling, who suggests the pope does not accept the implications of his own goal of integrating insights from disciplines beyond theology.

The discussion becomes more complex with the exploration of very technical advances in genetics and epigenetics. Evolutionary biology not only demonstrates that our views of gender and sexuality must change, it reveals the unpredictability of what that change might be. It is interesting to this apostate biologist turned theologian that modern thinking revisits Augustine’s biological “inheritance” of sin and agrees with it. Epigenetics demonstrates the ability of experiences—often tinged with evil—to influence the expression of genes in future generations. “Original sin” can be understood then as a “universal feature of human life,” that is, past evil continues to impact human beings and their behavior, passing epigenetically to future generations. Even “infected” cultural norms and narratives survive beyond their times and can affect the expression of identity.

The final section of the book connects all the unlikely “bedfellows:” Augustine, Darwin, John Paul II, the New Catholic Feminists, process theology, the #MeToo movement, and even the new Feminist Materialists. It suggests a path to the future. It makes the case for the evolution of sexual differences.

The book is dense—a creative all-you-can-eat buffet leaving the reader more than full. It does a good job of wading through a daunting survey of the relevant literature, picking out the nourishing main dishes and pairing them with appropriate “sides.” It adds a tantalizing dessert: Mary’s essential womanly role as the literal connective tissue that joins God with humanity.

Though difficult to plow through, this would be an informative and consoling read for anyone struggling with gender identity in themselves or others. Clearly how we think about “human” must be less rigid. The book would top my Christmas list for bishops and other clerics who are wedded to an outdated theology and take public positions on things sexual that contribute to pain, heartache and even suicide for many. The digital version of the book is off-putting, however. The dense content prompted this reviewer to turn to the audio version. The no-expression IT reader, which treated footnote numbers as if they were part of the narrative, was most annoying.