“Cleavage: Men, Women, and the Space Between Us” is an accomplished and witty memoir by transgender author and activist Jennifer Finney Boylan. Arriving some two decades after her trailblazing book, “She’s Not There,” this new entry reflects on differences between the genders, and how things have changed since Boylan was, as she puts it, “the media’s go-to person on trans issues.”

“Cleavage: Men, Women, and the Space Between Us” by Jennifer Finney Boylan. Celadon Books. $29

Today, at first glance, Boylan lives a nearly conventional life. She’s been married to the same woman for 36 years, has two grown-up kids, a dog, and she teaches at Barnard.

“Cleavage” at times has the feel of a road trip, with its many exploits and adventures: There’s James Boylan, the tearful son, telling his evangelical Christian mother that he was meant to be a girl, and hearing in response, “Love will prevail”; or James, the impish prep schooler, with his boyos, as he dubbed his male friends, getting stoned and listening to Frank Zappa. Then there’s Jenny, at home in her Maine kitchen, tossing a handcrafted pie into the pizza oven; or Jenny in Philadelphia, attending her 40th high school reunion.

“It was weird to be back (at school) after all these years with a martini and a vagina,” she says. Then later: “How do you build a bridge between your present and your past?” she asks. “What does it mean to be a woman who never had a girlhood?”

The book incidentally serves as a commentary on the state of being female in America. When James Boylan married his wife Deedie at the age of 30, he was a willowy 6 feet, 140 pounds A decade later, he weighed 185, without ever having given it a thought. Yet on the cusp of transition, that added girth was verboten. Boylan now believed she needed to be small — a challenge at 6 feet! — and thin, and to look and sound more female. She studied at length with a voice coach, who encouraged her to upspeak. She took hormones, grew out her hair, underwent facial electrolysis, started therapy. When it came to additional cosmetic surgery, she drew the line.

“I thought: well, I’m not going on this long journey to be a fashion model. I’m in it to become myself,” she says. “But also because I feared that if I really looked different, my wife would no longer love me. I know this seems insane, given the things that I was changing.”

Further, Boylan began to perceive herself differently in the world. She gained a new awareness of her physical vulnerability and risk of violence, becoming attuned to the sound of footsteps behind her at night. For most women, these facts of life are second nature. For the author, however, these insights speak to the inevitable late-bloomer aspect of her life as a woman.

More counterintuitive is Boylan’s view that it’s harder to come out now than it was two decades ago. Back then, she says, “Transness — to some people — seemed a thing as obscure as membership in the Royal Antediluvian Order of Buffaloes.” Today, by contrast, the political climate is far more inflammatory and dangerous.

But the most compelling episodes in the book begin with the author’s son, Zach, announcing, “Listen, there’s something I need to tell you.”

In the annals of irony, that “something” was, incredibly, that Zach, in his mid-20s, was en route to becoming Zaira. Some 20 years after the author’s own transition, her son was well along in the same process, already taking hormones, before sharing the news. “Deedie and I had both reacted as if we’d been struck by lightning,” Boylan says, admitting to having been clueless.

What followed was the inescapable anguish that a parent might feel in this situation, both poignant and wrenching. Later there would be a seafood confab on Cape Cod, where Maddy, as her kids call the author, and Zai have a heart-to-heart over fried clams. Each feared that she was failing and disappointing the other, as if someone were to blame.

“It has been remarkable, then, to watch the child for whom I had worried and wept, now emerging as a settled and centered woman in the world,” Boylan writes. “Of what had I been afraid? Was it really that my child’s transition would fail to bring her happiness? Or was I really in mourning for myself — that if my child turned out to be someone other than whom I had thought, that I, too, was not quite the parent I had convinced myself I had been?”

In the end, “Cleavage” takes readers to unexpected places, raising important questions and making the case for humanity in all its fullness. One quickly grasps how Boylan became the explainer-in-chief for trans issues. She has an easy candor; a wicked, bawdy sense of humor; and charm to spare. Foremost, this searching, eloquent memoir preaches Boylan’s gospel of love and kindness, which should be required reading for all.

Joan Silverman writes op-eds, essays and book reviews. Her work has appeared in numerous publications including The Christian Science Monitor, Chicago Tribune and Dallas Morning News. She is the author of “Someday This Will Fit,” a collection of linked essays.

READING

WHAT: Jennifer Finney Boylan reads from and discusses “Cleavage: Men, Women and the Space Between Us.”

WHEN: Monday, Feb. 10, 7:30 p.m.

WHERE: Space Gallery, 538 Congress St., Portland

TICKETS: printbookstore.com/event/jenniferfinneyboylan