In particular, your purchases aren't cap-weighted. You simply divide your portfolio evenly among women-lead companies. So aside from biases that might exist for women-led companies (they have to work harder, so they're better performers; or, they tend to be more highly represented in consumer cyclical, etc), you're also "over-weighting" small-cap equities, which have done quite well relative to the S&P500 (all large cap) over the period[0].

I would be interested in a breakdown of other factors, but I expect very little variance actually derives solely from gender of ownership once you account for other conventional biasing factors of the chosen index.

[0]: http://performance.morningstar.com/funds/etf/total-returns.a... (Compare to S&P500 TR)