"the relevant founder has been put on leave... The founder’s wife... will no longer be permitted in the office."

Almost exactly what I expected. As the startup grows larger (200+ employees now for Github?) it's not uncommon to have some cultural setback. +1 for Github trying to fix it asap, but still Chris Wanstrath did not mention how are they exactly going to fix the culture. Putting founder on leave is by no means panacea. The behavior on that one founder is very likely not the cause for the wrong culture, but just the side effect. So more specific plans INSIDE the company, please? (well, actually I think fixing the culture can't be done by any plan, but it must be done by example of founders/high-level executives.)