Sentence:  'I don't know why for sure,' she says. 'But I suppose, if I was Henry's mother, I would not want my child, a pretender, a usurper, king only by right of battle, taking his crown alongside a princess, a <WSD>true-bred</WSD> princess of the royal family, beloved of the people, and a beauty. Apart from anything else I would not like how it looked.' 
Meaning of the word marked with <WSD> tags:  Of a proper lineage.