I have reviewed the twitter documentation @anywhere where I can use User Object Properties but in the userdata I don't find the gender property.
When you create a twitter account it never asks for gender, so you cant get it through the API.
You would need some kind of AI to determine it.
Demographic data such as gender and age are not available from the API -- and not always appropriate as Twitter accounts can represent many things not limited to persons alive or dead.
Latest answer @2016
You still can't get twitter users' gender but can you can deduce it with some workable apis.
See node-cheat gender_by_name for all reasonable and tested solutions.
来源：https://stackoverflow.com/questions/12956757/how-can-i-get-twitter-current-users-gender