Why do women leave tech jobs? There's been lots of pontificating about this, but Kieran Snyder, who's held senior leadership positions at Microsoft and Amazon, and is CEO and co-founder at text analysis startup Textio, decided that getting the answer to this question shouldn't really be that hard.

She'd just ask women who had once worked in tech, but no longer did, why they left. And she'd ask lots of them. Snyder put out a call on social media, saying she wanted to women who were formerly in the tech industry. Via email, telephone and face-to-face conversations, she interviewed 716 women who had worked at 654 companies in 43 states. On average, they'd each worked in tech for seven years.

The answer: It's the culture, bro.

For geeky men who never fit in socially, brogrammer culture may be reassuring in a way that more anodyne corporate cultures are not. Not only are the nerds finally on top, but they’re encouraged to revel in their newfound status.

It doesn't work that way for women. While motherhood is sometimes the straw that breaks the camel’s back, so to speak, these camels were pretty unhappy before they became pregnant. Some 484 women, or 68 percent, cited motherhood as one of the reasons they left tech jobs. As Snyder writes in a post for Fortune:

Many women said it wasn't motherhood alone that did in their careers. Rather, it was the lack of flexible work arrangements, the unsupportive work environment, or a salary that was inadequate to pay for childcare. As Rebecca, a former motion graphics designer, put it, "Motherhood was just the amplifier. It made all the problems that I'd been putting up with forever actually intolerable."

Some 192 women, or 27 percent, said discomfort with the work environment, and either overt or implicit discrimination, factored in their decision to leave. Here’s how one front-end developer of eight years' tenure described it:

Literally 28 of the 30 people in our company were white, straight men under 35. I was the only woman. I was one of only two gay people. I was the only person of color other than one guy from Japan. My coworkers called me Halle Berry. As in, "Oh, look, Halle Berry broke the website today." I’m pretty sure for some of them I'm the only actual black person they’ve ever spoken to. Everyone was the same, and no one was like me. How could I stay in that situation?

Most of the women Snyder spoke with said they enjoyed the work itself. Many of the mothers said they would have stayed with their jobs, but their companies didn’t offer maternity leaves (companies with fewer than 50 employees aren't covered by the Family and Medical Leave Act), and they had to quit to have kids.

It strikes me, in reading Snyder’s collected stories, that the "cool kids" of tech are imposing on women the lousy environment they once suffered through--back when they were the nerds who got teased and hassled. Some of the women reported outright harassment, but more reported "something milder: the simple discomfort of not fitting in in an otherwise homogenous setting. It may not sound like a big deal if you’re used to being in the majority but it was enough to drive many qualified engineers to quit."

Of the 716 women Snyder spoke with, 465, or 65 percent, are not working today. Some 251, or 35 percent, are working in non-tech jobs, and 45 of those, or six percent of the total, are running their own companies. Ninety-seven percent say they're never coming back to tech.

This is an expensive problem, but the fact that these women are done with tech for good shouldn't surprise anyone. After all, would any of those once-scorned geeks, given a chance, go back to School Spirit Day to help fete the football team? Of course not.