tremere110: My understanding was that Witchers couldn't be biologically female. Something about the process kills them (and still kills most of the men anyways).
I suppose Geralt could be born a man and be a cross-dresser (gender confirmation surgery is likely out considering the state of surgery with medieval technology).
dtgreene: What about using magic in place of the surgery? (In a fantasy world, if one chooses to thoroughly explore the nature of transgender identity, one would have to consider the idea of magical transition.)
Also, I believe the process hadn't existed before the first book was originally written; hence, if the original author wanted Geralt to be female, the process would have been different.
By the way, how many books were there, and how many of them are currently covered by the computer games?
There are 7 books in total. The computer games are meant to be sequels rather than straight up adaptations, though the first game does have several scenes from the books deposited right into them. Probably because the game creators wanted to share these scenes and knew most of their audience would not have read the books.