A gene which is dominant shows their effect even if there is only one copy of that gene in the pair of alleles from their parents. When using a Punnent Square, dominant traits are shown by using a capital letter. An example of a dominant trait (Mack Snow) crossed with a Normal can be seen on the left.
A gene which is recessive only shows their effect if there are two copies of the gene in the pair of alleles from their parents. When using a Punnent Square, recessive traits are shown by using a lower case letter. An example of a recessive trait (Murphy Patternless) crossed with a Normal can be seen on the right.
A gene which is Incomplete Dominate has generally has three different appearances. The gecko homozygous for the trait and homozygous not for the trait will look different. In Leopard Geckos, the Mack Snow trait is thought to be Incomplete Dominate.
This refers to traits that were produced through selective breeding. Breeders selected the best examples of these traits in their collections and bred them together. Traits such as Tangerine, Hypo and Carrot Tail are all line-bred traits. These traits are not controlled by a pair of genes, but a selection of increase / decrease alleles. For example if you had a great specimen of a Leopard Gecko who had a 90% carrot tail and you bred it to a normal phase Leopard Gecko. What you would get is a diverse range of hatchlings showing varying amounts of Carrot Tail, some may even show no Carrot colour at all!
The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett, who devised the approach. The diagram is used by biologists to determine the probability of an offspring having a particular genotype. The Punnett square is a tabular summary of possible combinations of maternal alleles with paternal alleles.  These tables can be used to examine the genotypic outcome probabilities of the offspring of a single trait (allele), or when crossing multiple traits from the parents. The Punnett Square is a visual representation of Mendelian inheritance. It is important to understand the terms "heterozygous", "homozygous", "double heterozygote" (or homozygote), "dominant allele" and "recessive allele" when using the Punnet square method. For multiple traits, using the "forked-line method" is typically much easier than the Punnett square. Phenotypes may be assessed using a Punnet square, but the phenotype that may appear from a given genotype can be influenced by many other factors.
Het or Heterozygous
This means that the hatchling is carrying the gene for a specific trait but only one gene out of a pair is of the special trait. For example hatchlings could have a gene for Albino, Blizzard or Patternless but would not express the trait outwardly as only one half of a set of paired genes has the mutation.
This is the opposite of Heterozygous (Het) and means the the hatchling is carrying two copies of a specific gene one each from it's parents. This would cause the hatchling to express the given trait in its Phenotype.
Is used to describe the genetic make up of a hatchling whether it be seen or not, so a Blizzard Het Albino would be its Genotype, its Phenotype would be Blizzard as this is the only visible genetic trait that is outwardly displayed.
Refers to traits that are not expressed when combined with a dominant trait. All Albino, Blizzard and Patternless traits are recessive in Leopard Geckos.
Is used to describe the way a hatchling looks, for example if the hatchling is a Blizzard, Patternless or an Albino, where its genetic makeup can be visibly detailed this is the Phenotype of the hatchling.