Kintyra Septim was Pelagius' first cousin, and daughter of Tiber Septim's brother, Agnorith. A former Queen of Silvenar. Silvenar is a city in Valenwood. So does the fact that she was a queen in Valenwood mean that she married a bosmer king? How else would she be the queen of Silvenar. If she was married to a bosmer king then that would mean her children would have some Bosmer blood in them, despite them still being Imperials like her.
Could the fact that Tiber Septim's niece was married off to some Bosmer noble mean that Tiber came from a noble family or that his whole family was uplifted to noble status when he became Emperor?