Men invented the Internet. And not just any men. Men with pocket protectors. Men who idolised Mr. Spock and cried when Steve Jobs died. Nerds. Geeks. Give them their due. Without men, we would never know what our friends were doing five minutes ago.

But are these men trapped in the past even as they create the future?

That’s the debate that has sprung up here since Ellen Pao, a junior partner in her early 40s at the distinguished venture capital firm of Kleiner Perkins Caufield & Byers, filed a sexual discrimination lawsuit against the company and her colleagues there.

The complaint, laced with accusations of professional retaliation after spurned sexual advances, has riveted Silicon Valley, whose venture capitalists generally prefer media attention for their businesses and deals, not themselves. Instead of talking about the New New Thing, people are discussing an old, old problem. And they are taking sides.

Pao’s complaint goes further. It depicts venture capitalists here as a group of 21st-century men who may be hard at work building the 22nd century but, when it comes to dealing with women in the workplace, are stuck firmly in the caveman era — or at least in the 1950s. It’s a portrait that many women in tech find all too familiar.

“You talk to any woman in technology and she will have a personal story or know a story where she felt conscious of her gender in subtle or significant ways,” said Kathy Savitt, 48, the chief executive of the social commerce startup Lockerz. Sometimes, she said, it’s as mild as realizing, “I’m the only chick in the room.” Other times, “it’s a lack of relevance, a feeling you can see an end to your opportunities.”

With the number of women in Silicon Valley so meager, a prominent discrimination lawsuit does not surprise Savitt. This place runs into trouble with women on a regular basis, most memorably in recent years when the CEO of Hewlett-Packard resigned after inappropriate conduct with a former reality TV actress who was working for him.

The shock really stems from where the scandal is taking place. Savitt knows Kleiner well; the firm is financing Lockerz. She cannot comment on the suit but expresses her deep admiration for the Kleiner crew. The firm is one of the few exceptions to the venture world's disinterest in hiring women. A quarter of its 50 partners are female.

That fact fits awkwardly with the lawsuit’s claim that one male executive, Randy Komisar, told Pao that women would never succeed at Kleiner “because women are quiet.” Another male executive, Chi-Hua Chien, is quoted in the suit saying women were not being invited to a big-deal dinner because they would “kill the buzz.” Neither Pao nor any of the parties mentioned in the lawsuit would comment on it.

Kleiner always tried to take the valley’s sexism in stride “When men made passes, I just downplayed it so the guy doesn’t feel he’s being put down when rejected” — but is disappointed by its persistence. “I am shocked there aren’t more women in high positions in Silicon Valley,” Kurtzig said. “I always thought the world was going to be gender-blind.”

Pao, who came to Kleiner with the dream of helping direct such a fund, graduated from Princeton with a degree in electrical engineering. In 2005, she came to Kleiner as a junior partner, working as chief of staff to John Doerr. Pao’s role was to help Doerr identify investments, interview executives and write speeches. According to the suit, her troubles began almost immediately when another junior partner, Ajit Nazre, made inappropriate sexual advances.

Eventually, the complaint says, Pao “succumbed” to Mr. Nazre’s insistence on sexual relations on two or three occasions. When she put an end to the relationship, it says, he “started a consistent pattern of retaliation against her.” This went on for five years, it contends.

An account of the suit in The New York Times noted that in 2003 and 2006, workmen on Fletcher’s Connecticut estate had accused him of sexual harassment. Fletcher denied the allegations, which were settled out of court. He declined to respond to a request for comment. Before the marriage, Fletcher had lived at the Dakota with his longtime boyfriend, Hobart V. Fowlkes Jr.

Here are some of the cold stats: Women make up just 9.1 percent of the board members of Silicon Valley companies, compared with 16 per cent of Standard & Poor’s 500 companies, according to Spencer Stuart. The National Venture Capital Association estimates, based on a recent survey, that only about 11 percent of investing partners at venture firms are women. The ratio is not much higher for the entrepreneurs these firms back. In 2009, only 11 percent of companies that received venture backing had a female CEO or founder, according to Dow Jones VentureSource. It’s a retro state of affairs, although that isn't stopping Silicon Valley from protecting its own, which means Kleiner. One Kleiner-backed woman said in an interview that she didn’t think much of Pao’s suit.

“Anybody can sue anybody for anything, right?”Then she called back and said that she had now read the blogs and news articles about it, that the whole thing was a mess, that she was speaking out of ignorance and could she just stay out of it? Few lawsuits like this make it to a jury, but Pao's case might be an exception. And some on both sides want the case to go to trial. Any settlement by Kleiner could look like an acknowledgment of guilt. The firm, meanwhile, is playing as aggressive a defence as it dares, given the legal constraints.

Owen Thomas, a former Valleywag gossip columnist and a longtime Silicon Valley observer, saw the situation this way: “If a tenth of this is true, Kleiner Perkins has a problem.”

The women of the firm are certainly not united behind Pao. One of them, Beth Seidenberg, a general partner, took the unusual step of issuing a statement.

“I was drawn to the firm because of its diversity and have excelled here as have other women,” she said. “Everyone has an equal opportunity to succeed” at Kleiner. In an interview, she repeated those points.

Last week, Doerr posted a lengthy message on the firm’s website, saying Kleiner Perkins would “vigorously defend our reputation”. He did not mention his former aide by name. The next day, Kleiner announced that it was hiring a new female partner.