[big_maybe]

In my last job I led a dev team made up of 8 women and 1 man (we did internal front-ends). The rest of the programmers in the company, including web, platform, DBA, IT, QA, devices etc. had plenty of excellent women working there.

I don't know why this particular company didn't suffer from gender imbalance in their computer science depts. There was no "affirmative action" directive coming from above; we hired the best human for the job.

It's possible that success breeds success. The more women worked there, the more women were comfortable there. Many programmers had migrated from the business side of the company (which needed to be pretty technical) so that may have been a factor.