There’s been plenty of talk this week about the great gender blur, that deliberate erosion on the runways of a once rigid demarcation between conventionally feminine and masculine clothes.

That crossover was especially apparent in men’s collections quietly venturing onto women’s turf, that move an opportune nod to those progressive young urban women who have long been among the most avid consumers of luxury men’s wear with a funky street-wear provenance.

The tendency was underscored in unorthodox, though commercially sound, collections like those of Public School; the more showily perverse Hood by Air; and Telfar, an under-the-radar label that judiciously threaded a handful of women’s looks into the line.

To hear it from fashion insiders, it’s high time. “The whole perception of sexual orientation is being challenged by the millenials,” said Lucie Greene, the worldwide director of JWT Intelligence, the trend-forecasting arm of J. Walter Thompson. “Among the cohort of 12-to-19-year-olds defining Generation Z,” Ms. Greene said, “the lines between male and female have become increasingly blurred, and we’re seeing that reflected in the collections this week.”

The notion of gender neutrality is being gradually accepted at retail. “Stores are discussing all the time how they can figure out a gender common denominator for their fashion assortments,” said Ed Burstell, the managing director of Liberty of London.

Those stores are reacting, if languidly, to a well-established trend. “On the street these days,” Mr. Burstell said, “you can’t always tell who’s a guy and who’s a girl.” — RUTH LA FERLA