What word or phrase does your mother always say?
polygenic pol·y·gen·ic (pŏl'ē-jěn'ĭk)
Relating to a characteristic or disease controlled by the interaction of genes at more than one locus.
polygene pol·y·gene (pŏl'ē-jēn')
One of a group of nonallelic genes acting together to produce quantitative variations of a particular character.