We do know that Pharaoh Tutankamon, the son of Nefertiti and Pharaoh Akhenaten, had a lot of health problems. Most of those were – or seemed to be – standard inherited disease and genetic issues typical for children of inbreeding. Genetic analysis of the mummies of Tut’s other family members does suggest that Akhenaten and Nefertiti were likely siblings themselves. However, given the great timeframe of over three millennia, we can’t know for certain.