Dominant mutations are unique in that only one parent of a dominant mutation is required to produce the mutation in their offspring.

A bird cannot be split to a dominant mutation. As it's mode of inheritance is dominant then the bird will visually show it and all other mutations it is carrying will either be shown as a combination eg. Dominant Silver Pearl Pied, or it will be split to these mutations (ie. carrying them on their chromosomes ready to pass onto their offpring).

A single factor (SF) only carries one dominant gene on one chromosome. A double factor (DF) carries one gene on two X chromosomes (which will in turn make for one base pair in their DNA), hence only cocks can be DF as they are XX and hens are XY.

Sometimes termed semi-dominant or partial dominant. Therefore:

A bird can inherit the mutation from only ONE parents to visually show the effects of the mutation. These birds are termed single-factor;

Recessive mutations require both parents to be carrying the recessive mutation, either visually or split, in order for the mutation to be produced visually within their offspring. For example: if you mate two pieds together, and you will get 100% pied offspring, if you mate a pied to a split pied, a clutch ratio of 50% pied will be produced, and therefore if two split pieds are mated , they will have 25% pied offspring.

Hens can be split to a Recessive mutation.

Sex linked mutations are carried on the X chromosomes. Cocks have 2 X chromosomes (XX). Hens have an X and a Y chromosome (XY). Sex-Linked mutations must be carried on both X for cocks, and the single X on Hens, for the mutation to be visible.

Cock's are split to the sex-linked mutations when only one X chromosome is carrying the sex-linked gene.

Hens cannot be split to a sex-linked mutation, because the mutation is on their X chromosome and as they only have one X chromosome, the mutation has to be visible.

Both Pastel and Whiteface control psittacin dilution and are recessive to the Wild-type, but Pastel is dominant to Whiteface. So:

Wild-type can be heterozygous (aka split for) Whiteface OR Pastel, but not both simultaneously;

Pastel can be heterozygous (split) Whiteface;

...but Whiteface cannot be split to Pastel - if it were, it would be a Pastel as the Pastel gene is dominant to the Whiteface gene.

Both Fallow and NSL Ino control melanin dilution and are recessive to the Wild-type, but Fallow is dominant to NSL Ino. So:

Wild-type can be heterozygous (aka split for) Fallow OR NSL, but not both simultaneously;

Fallow can be heterozygous (split) NSL Ino;

...but NSL Ino cannot be split to Fallow- if it were, it would be a Fallow as the Fallow gene is dominant to the NSL Ino gene.

A Whiteface Lutino is the phenotypic result of the co-dominance between the autosomal recessive gene and the sex-linked recessive gene i.e. combination of both genes rsulting in the visual representation of BOTH colour mutations. The Whiteface gene prevents the depositistion of all psittacin pigmentation and the Ino gene removes all melanins, and so resulting in a bird which is completely devoid of pigment.

So a Whiteface Lutino is a pure white bird with red eyes, pink beak, legs, feet and clear claws.

Whiteface Lutinos are impossible to visually sex. So you must sex the bird by using either the genetics and pedigree of the parents, by DNA analysis or by watching its behaviour - cocks sing, whistle and display.

Whiteface Lutino cock

Whiteface Lutino hens

Basically a double-Pallid Cockatiel, but known as the Platino due to the combination (co-dominance) of the (Pallid) and genes.

The Platino is a very pale silvery-yellow bird with slightly darker flight feathers, red eyes, pink beak, legs, feet and clear claws.

Platino can only occur in the cock due to it's sex-linkage, requiring two XX chromosomes - 1 for Platinum, and 1 for Ino. Therefore cocks can be Wild-type split (aka heterozygous) Platinum OR Ino - not both), homozygous Platinum, homozygous Ino or co-dominant Platinum and Ino: Platino.

Due to the XY chromosomal structure, hens therefore only have 1 X chromosome and thus can only either be Wild-type (i.e. split or heterozygous Platinum OR Ino - again not both), homozygous Platinum or homozygous Ino, not both.

Platino cock