There has only ever been one woman who has reached the standard of GM - Judit Polgar. No other woman has come close to her (yet).
FIDE introduced the WGM title (and WFM, WIM etc) to encourage women into chess and to develop their skills alongside other women. I think the ELO for WGM is 200 less than GM standard.
My son plays at a decent level and in his chess club there are only a handful of women out of the 50+ registered players.
In the past decades the main chess playing nations were USSR and USA and they treated chess as an extension of the cold war! Women were just not encouraged, Countries like China and India are now investing heavily in chess development but neither of these countries is really known for it's forward thinking when it come to sex equality, although it's good to see some really strong girls from these countries in the junior tournaments.
Chess is wonderful, and something in which women could truly excel if given the right encouragement and support. It's opportunity over the past decades they have lacked, not innate capability.