"6. any person may become the spouse of the monarch. so there's a lottery opportunity to become majestic that is open to everyone. our kate won that race in this generation. so the next heir is half common. which is awesome."
"Prince William and Kate Middleton also share some royal ancestry, again through his mother’s family. The mother of those twins raised at Gilling Castle five centuries ago descended from both King Edward III and King Henry III. Again, it was a maternal line that went back to the Plantagenets."
So long as she is bloodline Alea,.........
http://suite101.com/article/prince-william-and-kate-middleton-share-ancestors-a353582