Wallis Simpson has been demonized for decades as the Baltimore divorcee who scandalized Britain by luring Edward VIII, the Prince of Wales, from his short tenure on the throne.
His abdication -- touched on in the 2010 film, "The Kings Speech," and most recently in a sympathetic biopic from Madonna, "W.E." -- caused an unprecedented constitutional crisis in 1936 and she was thereafter seen as "that woman."
And now, a new biography, "That Woman: The Life of Wallis Simpson," suggests that the "mannish" social climber with the "beautiful dark sapphire blue eyes, full of sparkle and nice mischief" may have been intersex.
Author Anne Sebba points to the Duchess of Windsor's raspy voice, square jaw and flat chest as signs, among other physical manifestations, that she was born male.
She describes a flirtatious debutante with a voracious sexual appetite, trained in the Chinese art of seduction and comfortable with oral sex, an unlady-like talent in the early 20th century.
An estimated 1 in 2,000 children born each year are neither boy nor girl -- they are part of a group of about 60 conditions that fall under the diagnosis of disorders of sexual development.
Once called hermaphrodites, from the handsome Greek god who had dual sexuality, they have been described in literature for centuries, from Judaism's the Talmud, to the Pulitzer-winning novel, "Middlesex."
"People from time immemorial have had accidents of nature and presented kids with partially formed genitals that they didn't understand," said Dr. Norman Spack, an endocrinologist and co-director of the Gender Management Service at Children's Hospital in Boston.
Simpson was born in 1896, has been dead for 26 years, and it is highly unlikely anyone will ever know if she was truly intersex, he said.
As for speculation that her "mannish demeanor" is evidence of being intersex, Spack said he has "scientific and philosophical problems" with that premise.
The biography suggests that Wallis may have been born with complete androgen insensitivity syndrome (CAIS).
Those born with CAIS are fully female, except for the absence of a uterus or ovaries, so they can neither menstruate nor reproduce.
Girls with CAIS have the male XY chromosomes, but because the hormonal virilization process does not occur in the early stages of gestation, they never develop external male genitals -- they remain female -- or internal female organs such as ovaries or uterus. As a result, they are infertile.
"There are several prominent actresses today in America -- I can't reveal their names -- who have CAIS," said Spack. "They are mothers with adopted children and they are women, of course."
These women can have sexual intercourse and they also report normal sensation, because nerve endings are still present.
And, according to Spack, "CAIS girls hardly ever struggle with gender identity problems."
Children with CAIS have a mutation in the androgen receptor gene that makes it impossible for the body to deliver testosterone to the developing fetus.
The genetic defect is carried in the mother's X chromosome and passed on to 50 percent of their male children, who "come out looking female," according to Spack.
In the first six to seven weeks of gestation, the genital area is undifferentiated. "There is no difference between the sexes," he said. "The structures can go either way."
Male hormones stimulate the tissue to form a phallus, seminal vesicles and sperm ducts, rather than a clitoris, uterus and Fallopian tubes.