Well, I'll give you a
hint.
Cockatiels have two pigments, melanin and lipochromes. Cinnamon mutation changes the expression of melanin, normally cockatiels are a dark gray color, into a brown-gray.
Cinnamon is sex-linked mutation, and as a note female birds have XY and males have XX chromosomes.
Whiteface is a recessive mutation, and means that there are no yellow or orange pigments.
Pied is also recessive, but to be split means that the bird carried one copy of this recessive gene and shows it. Maybe the bird has one light colored toenail, or maybe (like my bird) they have a small patch of white/yellow on the back of their necks.
We know that my bird is female because she doesn't have a nice, white colored head like a male white face would. She has a higher chance of being a female just because of her mutation, and she can't carry the gene the way a male could. It's the opposite of say, color blindness, which is X-linked in humans. It has everything to do with the sex chromosomes.
Cockatiel color mutations are awesome.
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