The last of this city’s Fashion Week revelers have drained their champagne glasses and the seasonal fashion train begins to roll through London, Milan and finally Paris, where the runway presentations wrap up in October. The global search is on for all that is new and different. But one notion remains stubbornly unchanged from city to city, year to year.

The stereotype of the gay designer is so deeply ingrained in the culture that it is often assumed to be a fact. Whether industry insider or casual observer, people often presume that a male designer is gay until he announces himself otherwise. And while there are a host of successful, brand-name women in the industry, lesser-known ones have gone on record about feeling disadvantaged because of decision makers’ subconscious belief that gay men make better designers.

There are no statistics about the numbers of gay men in the fashion industry. And, as fashion historian Valerie Steele once noted, “there is no gay gene for creativity.” But the fashion industry has been undeniably more welcoming of openly gay men than other fields have been.

Yet no one in the mainstream has ever tried to examine the impact of homosexuality on fashion, says Steele, who is director and chief curator of the Museum at the Fashion Institute of Technology (FIT) in New York. “It had only been done in LGBT centers, and it had only focused on gay imagery in fashion.”

From an academic, historical and cultural point of view: “It’s like an open secret,” Steele says. “Gays and lesbians had been hidden from [fashion] history.

“We’re putting them back in.”

A Queer History of Fashion: From the Closet to the Catwalk” opened Friday at the Museum at FIT and runs through Jan. 4. Steele and co-curator Fred Dennis spent two years researching the extent to which gay men and lesbians worked in the fashion industry and the ways in which their participation shaped aesthetics. By far, however, gay men received the bulk of the exhibition’s attention.

The exhibition’s most poignant moment — and certainly its ripped-from-the-headlines one — is when it acknowledges the demise of the Defense of Marriage Act. Two understated business suits — one in midnight blue, the other in a slightly lighter shade of navy — represent this summer’s upending of DOMA by the Supreme Court. The suits are the wedding ensembles worn by Steven Kolb, chief executive officer of the Council of Fashion Designers of America, and his husband, Jay Inkpen, a freelance producer. The two men were married Dec. 27, 2012, at New York’s City Hall — a fact that Kolb tweeted to the world.

Kolb’s two-button Rag & Bone suit and Inkpen’s midnight-blue one from J. Crew are the epitome of modern American menswear — completely devoid of subversive subtext. The suits, despite subtleties of silhouette and lapel width, are utterly traditional. The fact that a community’s journey from red velvet cloaks worn in the shadows, to leather harnesses worn in protest, to transparent trousers worn in defiance finally comes to rest on business suits that would not be out of place if worn on Capitol Hill is testament to the power and reach of fashion itself and the influence that gay men and women have had on it.

The exhibition begins in the 18th century, when both men and women dressed to reflect their place in society.

Men styled themselves to display power and wealth. Their ability to bed anyone they pleased, whether male or female, was an extension of that omnipotence, Steele says. To be a peacock — with the flourish of a patterned handkerchief, a colorful bow tie or a jeweled brooch — was to be an influential aristocrat.

But soon, cross-dressing “mollies” and effeminate “macaronis” from meager circumstances began to gather in secret societies, private clubs and dark corners — causing a stir by blurring gender lines. Dandified style started to become egalitarian — far too democratic for the power brokers’ taste. Capitalism’s rising industrialists rejected color and frippery, leaving it associated with homosexuality.

The 20th century introduced the era of hyper-masculinity and swagger, which emerged in the years after the 1969 uprising at New York’s Stonewall Inn. The working-class, tough-guy costuming — cut-off denim, work boots, leather chaps — signaled the start of the modern gay rights movement.

The 21st century brought gay men who were crafting traditional styles yet assembling them with more glamour and greater sex appeal. And, wearing them with more confidence.

The sensibility was not part of some secret, coded language among outsiders; it was the accepted language of fashion — definitive and admired. Indeed, the hip-hop icon Jay Z doesn’t just mention the designer Tom Ford — who shrewdly has used his appeal to both gay men and straight women in his fashion seduction — in his music. The rapper recorded an ode to him in which he declares: “I don’t pop molly, I rock Tom Ford.”

The FIT exhibition seeds a conversation about the way in which designers — whether gay or identifying somewhere closer to the middle of the sexual spectrum — have used fashion as their own form of self-definition and have wrestled with notions of femininity vs. masculinity in their collections. Ultimately, it asks how those machinations have altered the culture at large. Today more than ever, people are comfortable addressing sexuality. Straight men make jokes about being metrosexuals. They will dabble in fashionable flourishes. They will, upon occasion, be peacocks. “But still, people will ask if something is too gay,” notes author Hal Rubenstein in an exhibition video.

New York’s rising stars, such as womenswear designers Jason Wu and Peter Som, do not blur the lines between genders. For spring 2014, they created clothes that caress the body or are enlivened with cheerful colors and floral prints. Theirs is a woman-on-a-pedestal approach to femininity.

Marc Jacobs — who has more publicly tested social mores by, for example, posing for his own men’s fragrance advertisement with nothing between him and an X-rating but an oversize bottle of cologne — expressed a darker, more confrontational aspect of femininity with a spring collection of dark-hued skirts and dresses embroidered with black flowers and sprinkled with jet beading. Where traditional tropes of womanhood reveal the body and pay homage to it, Jacobs’s collection soared on a woman’s ability to be strong and independent.

Thom Browne, who began his career in menswear, created a spring collection of molded white jackets and elaborate lace dresses that spoke of how social rituals — weddings, christenings, debutante balls — often constrain a woman, defusing her power and independence. If men are tricked into believing they must be tough, emotionless and sober, women risk being declared hysterical — difficult, shrill — when they refuse to conform to social expectations.

In Milan this week, when the designer Jil Sander — one of the few well-known lesbian designers represented in the exhibition — presents her eponymous collection, guests will expect an iteration of the austere minimalism upon which she built her reputation. She comes at femininity by denouncing its excesses. She has succeeded in giving generations of well-to-do women a professional uniform that does not try to imitate masculine dress but that is not chained to idealized femininity. Her work is not androgynous. It simply offers an alternative vision of how a woman can declare her sexuality.

And later this month in Paris, the American designer Rick Owens, whom the exhibition highlights as bisexual, will unveil a collection for a brand that deftly blurs the line between masculine and feminine. His models routinely wear floor-length dresses and sweeping tunics that could just as easily serve as a contemporary take on the djellabas worn by men in North Africa. And when Owens appears on the runway to take his bows, he is often wearing a skirt over his trousers, along with the same high-heeled footwear as his models.

Of course, simply because designers are gay, lesbian or bisexual does not mean that sexuality must be a central theme in their work. Sexuality is not identity. After all, designers of color are not always grappling with race or ethnicity in their collections. Sometimes a dress is just a dress.

But “A Queer History of Fashion” offers examples of occasions when fashion has made memorable statements when words were elusive. Eloquent messages of hope and anger are in the myriad one-of-a-kind garments and T-shirts made in support of AIDS awareness campaigns by designers such as Geoffrey Beene and Franco Moschino. Heartbreaking truth is visible in the emotional work of designer Alexander McQueen, who committed suicide in 2010. He described his fashion as an expression of his inner life.

The exhibition is a reminder that it’s just as important to look at what is being said, as it is to listen. “Fashion is communication in a way other than speaking,” Steele says. And when people are silenced, whether in New York in the 1950s or Russia today, fashion can be the only way for them to tell their story.