"In the most recent batch (W15), we asked about gender on the application form for the first time. The percentage of startups we accepted with female founders was identical to the percentage who applied."

There are application videos and have been for a while. And each founder has names listed on the application. With https://gender-api.com/ you could probably figure out gender without asking explicitly and could have done so acceptably well with previous classes. I would be curious what the stats look like back tested against each class over time.