So was Jenner always a woman trapped in a man's body? The answer according to his (her) transition miniseries is yes (complete with tales of sneaking into his mother's closet to wear her clothes).
Sounds like that is the case for her, then. Can't say I've been keeping up with that particular story. One of my friends has had a similarly-describable situation from a very early age as well.
Though again, using that phrase is lumping everything into one essentialist label that says everything rather than decomposing it into the potentially more useful descriptive subcategories 'how one wants to be considered socially', 'the body one wishes one had' / 'the body one is willing to have given current medical technology and the costs and tradeoffs thereo...
This thread is for asking any questions that might seem obvious, tangential, silly or what-have-you. Don't be shy, everyone has holes in their knowledge, though the fewer and the smaller we can make them, the better.
Please be respectful of other people's admitting ignorance and don't mock them for it, as they're doing a noble thing.
To any future monthly posters of SQ threads, please remember to add the "stupid_questions" tag.