According to a major DNA study released in 2010, which involved 10 mummies closely related in some way to King Tut, a high degree of inbreeding characterized the boy king's family.
Producing the most reliable five-generation pedigree of Tutankhamun's immediate lineage, the study, led by Dr. Zahi Hawass, the former head of Egypt's Supreme Council of Antiquities, revealed that King Tut was most likely the child of the "heretic" pharaoh Akhenaten.
Yuya and Thuya were recognized as his great-grandparents, while Amenhotep III and the mummy known as the Elder Lady (KV35EL) were found to be his grandparents. The mummy known as KV55 -- most likely Akhenaten -- and KV35YL, the Younger Lady, were identified as siblings, as well as King Tut's parents.
"This means Akhenaten married his own sister. We also know that the Younger Lady, King Tut's mother, can't be Nefertiti at all," Hawass told Discovery News.