# Zee QFT book on the neutrino mass

in p.102 of Zee QFT book,

"As of this writing, it is not known whether the neutrino mass is Dirac or Majorana. We will see in chapter VII.7 that a Majorana mass for the neutrino arises naturally in the SO(10) grand unified theory."

Question: However, what Zee said is puzzling --- the neutrinos in the SO(10) grand unified theory are in the 16 dim representation of SO(10), which carries chiral charge so the neutrino cannot be a Majorana. Am I correct? I think what Zee wanted to say is really breaking SO(10) to SU(5), and make the neutrino to be singlet 1 representation in SU(5), so we can give Majorana mass ONLY to this 1 representation of SU(5).

Am I correct?