The whole disaster that was Queen Mary I started when Princess Catherine of Aragon's "precious" sick betrothed Prince Arthur died, and left a "healthier" "more manly" kid brother, Henry, behind to marry. Catherine, having always had the hots for this kid, immediately leapt upon the opportunity, allowing Henry to give her syphilis, and her to give it congenitally to her future daughter Mary I herself. Apparently, syphilis was spreading like a bull on beer in those days.