[Misstiel]

It's because he is a pied. When a cockatiel is pied, they look the same even after their molt. He's what's considered as having a dirty face. I have two pieds, one male and the other female, and they both have grey and yellow on their face. The one on the top is the male; he has what's called a dirty face. The one below is the female, and she has more yellow, looking like a male, yet she is a DNA'd female that's even had chicks before. That's what's so unique about pieds. Not every one is the same.