Roxanne Roberts is a feature writer for The Washington Post.

As a general rule, I’m not all that interested in the sex lives of famous people — or unfamous people, for that matter. Be responsible, have fun, and don’t frighten the horses.

But there’s a case for literary voyeurism when the famous person is famous for writing about sex. “Coming of Age,” a new biography of Margaret Mead, with the provocative subtitle “The Sexual Awakening,” peeks under the covers in the name of academic research: How did a young woman from Pennsylvania become one of the world’s experts on sexual mores?

Before reading this book, I knew three things about Mead. She was America’s best-known anthropologist. She studied the sex lives of adolescent tribal girls. And she was short.

“Coming of Age” by Deborah Beatriz Blum. (Thomas Dunne Books)

Author Deborah Beatriz Blum, who was a graduate student when she met Mead in 1972, promises a tale of sexual discovery. The book is based on five years of Mead’s life — from a 20-year-old student at Barnard in 1921 to 1926, when she was a 25-year-old researcher in American Samoa.

Now I know all about Mead’s early romances, flings and ambitions. I know when she lost her virginity and when she cheated on her husband and lovers, male and female. Turns out her trip to the South Pacific, despite Blum’s poetic narrative, did little to change her beliefs about sex.

Mead didn’t take no for an answer, in life or in love. “I’m going to be famous someday,” she explained to her father when she told him she intended to use her maiden name after her marriage in 1923. “And if I’m going to be famous, I’m going to be known by my own name.”

Plenty of famous men and women achieve great things because of their single-minded focus, although Mead took it to another level. On her wedding night, she insisted that her groom sleep in a separate room. “I have a seminar paper to write,” she told him.

By the end of the book, I didn’t much care for Mead as a person or as a scholar. It’s surprising to read such a detailed biography without finding something to like about the subject. I got through it without finding a single real example of unselfishness or generosity. Mead, it seems, was brilliant, charismatic and a spoiled brat.

Blum tells her story through thousands of letters and memoirs written by Mead, first husband Luther Cressman, mentor and lover Ruth Benedict, and fellow academic and lover Edward Sapir. Luther loved Margaret. Ruth loved Margaret. Edward loved Margaret. Margaret loved Margaret.

Poor Cressman. The seminary student fell in love with Mead when she was 16, and the two, both still virgins, married six years later. He was her best friend and a lifelong afterthought, someone Mead had no guilt leaving back home while she pursued other loves.

One was Benedict, a young anthropologist in New York. Blum never explicitly addresses the issue of Mead’s bisexuality but makes it clear that Benedict, a loving mentor and confidante, became something much more. “Once under the sheets together they began to explore each other’s bodies, Ruth stroking every part of Margaret and Margaret quivering with pleasure under the touch,” writes Blum.

And then there was Sapir, the brilliant protege of Franz Boas, head of Columbia’s anthropology department. Benedict and Sapir were close friends — she was half in love with him — but Mead decided she wanted the recent widower for herself. The two embarked on a passionate, tortured affair: Sapir obsessed, Mead annoyed by his jealousy, and Benedict stuck in the middle as they both poured their hearts out to her.

But for all the sex, there’s not much of the promised “awakening.” Blum writes that Mead believed in polygamy but doesn’t explain how a young woman from a seemingly conventional family developed that view. A bitter Sapir called it “a mere rationalization. Having made her erotic life a mere tentacle of the ego, she could not possibly allow herself to pay the price of love.”

Nor does Blum tell us much about what Mead thought of her exploits. Did the earth move? Did her affairs change her sense of her own sexuality, or of women or men? Did it inform her research in the field? We don’t know.

So the sex, which is the reason most people will pick up the book, is kind of a purple-prose “meh.” The real shocker? Mead’s research in American Samoa.

Shrewd and strategic, Mead understood that she needed to explore an unknown culture to make her professional mark. At Barnard she had studied tribal tattoos in Polynesia and wanted to continue her research overseas. Boas had a different idea: He suggested she focus on adolescent girls instead; the nature vs. nurture debate was a hot topic in the academic world, and Boas thought his young student might bring back some interesting results from a non-Western culture. With a research grant in hand, Mead left for the South Pacific in the fall of 1925.

I naively assumed that Mead spent years living among the indigenous tribes to learn their culture and mores before writing “Coming of Age in Samoa.” She actually spent just nine months: the first two living on an American naval station while taking language lessons, then moving in with an American family on a nearby island.

It took three months for Mead to compile a list of 66 local girls she hoped to interview, but a hurricane badly damaged the island and prevented her from spending time with them. By January, she wrote to Boas, saying her fieldwork was “too short to justify even tentative conclusions.”

Just two months before she was scheduled to return home, Mead spent a few days with two young Samoan girls who told her what she wanted to hear: that tropical adolescents were sensual and carefree, just as she had imagined. That, along with a newlywed who told her that young Samoans had sex up to 15 times a night, convinced Mead she had enough evidence for her theory.

“The neuroses accompanying sex in American civilization are practically absent, such as frigidity, impotence and pronounced perversions,” Mead wrote excitedly to Boas: “I feel absolutely safe in generalizing from the material I have.”

Notebooks filled, Mead set sail for home in May 1926. On the six-week voyage to France, where she was to reunite with her husband after nine months apart, she met and fell in love with Reo Fortune, a handsome psychology student headed to Cambridge.

Fortune refused to sleep with her during the trip, which of course made Mead desperate to have him. Shortly after landing in Marseilles, she told Cressman she was in love with another man and planned to continue the affair. She also broke the news to Benedict, who had sailed to Europe to spend two months alone with Mead.

And then the book . . . stops. The epilogue explains that Mead returned to New York and divorced Cressman, married and divorced Fortune, married and divorced anthropologist Gregory Bateson, and finally settled down with yet another anthropologist, Rhoda Metraux.

But first, she decided to write her research for a general audience instead of fellow scholars. “Coming of Age in Samoa,” published in 1928, was an academic miss (British anthropologist A.C. Haddon dismissed Mead as a “lady novelist”). Even allowing for the kind of pervasive sexism from older male colleagues toward a young female graduate student, Mead’s methodology was a conclusion looking for facts, not the other way around.

But the book was a popular sensation for the “Flapper of the South Seas” and launched Mead’s career as a public intellectual, social critic and feminist hero until her death in 1978. Blum’s book ends when Mead was just 25 years old, so we don’t learn how her views on love, marriage and sex may have evolved over the years.

Which is just fine — one book on Mead is enough to last a lifetime for me.

Coming of Age
The Sexual Awakening of Margaret Mead

By Deborah Beatriz Blum

Thomas Dunne. 322 pp. $26.99