Toward the end of the century, Westerners who fled their home countries to fight in Afghanistan or Bosnia shared a common characteristic: They were practically all men. Today’s militant recruits, however, represent a dramatic demographic shift.

Most are just entering adulthood. They often meet terrorists online. They’ve asked in covert chats: Do you have hair dryers, or should I bring one?

One in seven are women, according to a new report.

An estimated 4,500 Westerners have ditched home for the Islamic State or other Sunni jihadist groups in Syria or Iraq. Researchers at New America, a nonpartisan think tank in Washington, D.C., collected data on 474 of these cases. They found in news reports an unprecedented number of radicalized women sneaking across borders.

“They often appear to be typical teenagers,” said Brigitte Lebans Nacos, a political science professor at Columbia University who studies terrorism. “They ask about hair dryers. They’re looking for romance. They’re fans of ISIS, like others are fans of pop stars.”

The average age of women in New America’s data set is 21. A third of the female converts are teenagers. Many are active in jihadist Web circles, occasionally using Twitter to connect with recruiters. Others have familial ties to jihadism — relatives fighting in Syria or Iraq, a lover who’d dedicated his life to the cause.

Roughly 250 Americans have attempted to join jihadists in Syria, according to government estimates. One in six are women. They display similar traits to Western fighters overall: young, digitally savvy and connected through blood to jihadism.

Erin Marie Saltman, a counter-extremism researcher for the Institute for Strategic Dialogue, said observers seeking to understand the phenomenon should forget gender stereotypes.

Many female recruits are drawn to Islamic State Web propaganda, Saltman said, which depicts women as “lionesses” working with men to build an extremist utopia. Some teenagers, still struggling to understand who they are, may embrace the hyper-conservative and violent ideals as they reject their own materialistic cultures. Others express anger over the perceived persecution of Muslims and a desire to find a sisterhood with similar beliefs.

“These women are denying being sexual objects of the West,” Saltman said. “They refuse to be objectified. They use the veil so they cannot be sexualized.”

In April, Buzzfeed published an interview with a 20-year-old American woman who ran away from her home in Alabama to marry an Islamic State fighter in Syria. The interview was conducted over the messaging app Kik, making it impossible to verify who actually typed the responses or whether they were coerced.

The woman, identified by other outlets as Hoda Muthana, spoke of finding no friends with mutual values in her home town.

“I literally isolated myself from all my friends and community members the last year I was in America,” she said in the interview. “As I grew closer to my deen, I lost all my friends, I found none in my community that desired to tread the path I was striving for.”

The reality she encountered in Syria is probably far from the happy partnerships perpetuated online. Experts believe everything an Islamic State woman sends into cyberspace is monitored by a man. “You’re not being allowed to go online and say ‘#gloomyMonday in the caliphate,’” Saltman said. “We know we’re looking at propaganda.”

Women in the caliphate cannot leave their houses without their husband’s permission. Those who lose their spouses in battle are forced to quickly remarry. They aren’t permitted to engage in battle, unless an emergency calls for last-resort soldiers.

Earlier this year, the al-Khanssaa Brigade, an Islamic State women’s group, released a manifesto that outlined a female fighter’s duty.

“Her creator has ruled that there was no responsibility greater for her than that of being a wife to her husband,” according to the English translation by Charlie Winter, senior researcher at the Quilliam Foundation in London. The document stated that girls as young as 9 may marry.

The Post’s Kevin Sullivan recently visited a refugee camp in Jordan, where he met women who said they’d escaped the grasp of the Islamic State. His interviews support evidence that women in the caliphate are second-class citizens.

“Those women, usually drawn by romantic notions of supporting revolutionaries and living in a state that exalts their religion, can quickly find themselves part of an institutionalized, near-assembly-line system to provide fighters with wives, sex and children …” Sullivan wrote. “Many local women find the restrictions extreme, backward and terrifying.”