Different morphs have different genes. Some genes are dominate, some recessive. Different genes contribute to different traits, such as eye colour or pigment.
a morph is a colour (or physical) mutation for instance albinism takes away the melanin (black) pigment and hypo (hypomelanism) reduces the amount of spotting.
a morph can be recessive, dominant or co-dominant
a recessive morph needs two copy's of the gene to be visually that morph an animal with one copy of the gene is heterozygous (het) and looks normalbut carries the gene
a dominant morph can be visually that morph with 1 or 2 copy's of the gene which are visually indistinct but are still different from normals
a co-dominant morph is where an animal with one copy of the gene looks different from a normal and when an animal has two copy's it is different from the one copy generally known as a super form
then there are polygenic traits such as tangerine which have been line bred for more orange colour rather than being a gene mutation
hope this helps here are some links to websites with morph information: Leopard Gecko Genetics Calculator Category:Morphs - Leopard Gecko Wiki