There are two stereotypical genders. Hence binary. In this context a binary person would be one who identifies as one of the two stereotypical genders.
No one ever asked us before if we identify with a gender so I wouldn't know what to say. If asked I would say that my gender is a biological woman. Gender seems to be like having a nationality or a passport - if you fill some forms and become a dual national you can fly out of the country on one passport, enter the country you are a dual national of on a different passport, when you want local hotel rates rather than pay international rates you produce the passport of the country you are in.
Not sure how these stereotypical genders were decided and which particular stereotype is the defining one that tells you which gender you should choose - might have to identify as different genders at different times of the day E.g. when you need the toilet and one seems to have a shorter queue you can be relevant gender for the less busy toilet, when you're in a sinking boat where traditionally women and children are rescued first you can pick your appropriate gender e.g a biological woman who is feeling chivalrous and is a strong swimmer might have to call herself a man during the rescue.
Kier Starmer seems to be unsure what makes a person a man or a woman - he's not the only one. It's confusing - if you find wearing trousers more comfortable and don't wear make-up and enjoy driving should you identify as a man during those activities and if you like cleaning the kitchen and getting the laundry done do you identify as a woman when ticking those chores off your list regardless of your biological sex?
