To me, it seems like this sort of problem occurs more in start-ups because the boundaries between professional and personal lives are blurred.
I've heard similar stories from people working at Facebook as well. This sort of forced camaraderie to fit into the clique isn't healthy at all. When I worked at Microsoft, we had quite a few talented female engineers on our team. I don't think at any point their gender was brought into question or discussion. We'd just solve problems, write code and have the occasional team lunch where we'd talk about the latest software paradigms, competition etc and go home.
I don't have any insights into start up culture (the only one I've actually been involved in is mine, There are two of us.) but I have worked for massive companies where management was pretty evenly divided by gender and have never personally witnessed anything untoward (or actually heard about and that place was a gossip mill).
I've heard similar stories from people working at Facebook as well. This sort of forced camaraderie to fit into the clique isn't healthy at all. When I worked at Microsoft, we had quite a few talented female engineers on our team. I don't think at any point their gender was brought into question or discussion. We'd just solve problems, write code and have the occasional team lunch where we'd talk about the latest software paradigms, competition etc and go home.