As we know Henry IX of England and Ireland son Henry VIII Tudor and Katherine of Aragon was one of England's greatest and learned kings. Being forced on to the throne at 17 after the untimely death of his father, he remained a defender of Catholicism while also allowing Protestants who swore personal loyalty to the Crown to be free to pursue their faith in private. His marriage to Margaret Stewart cemented the later of unification of Britain under one crown 87 years later.
Imagine if he was born a female. His father Henry VIII was obsessed with having sons I could imagine Europe being irrevocably changed. England might even go Protestant! However, Henry IX had brothers like Alexander, the Archbishop of Canterbury and Charles, Duke of Calais.
Let me know what could happen
OOC: I'm planning on writing a Tudor timeline and I am using this as a semi-brainstorming thread