i heard lavender isn't something genetic, that the morph is caused by something in the incubation, is this true? and if it is, what is the 'incubation thing' that makes lavenders?
Lavender leopard geckos are line bred. But, incubation has some influence on color. It is debatable on how influential the incubation temperature is, often eggs incubated at lower temperatures produce dark babies than eggs incubated at higher temperatures.
It's not that lavender "is not genetic," leopard geckos must carry the gene(s) that code for the protein(s) that can produce this trait. However, several breeders have observed that this color is expressed best or enhanced when incubating at around 84-86 degrees.