Polygenic traits are traits determined by the combined effect of more than one pair of genes. Human stature is an example of this trait. The size of all body parts from head to foot combined determines height. The size of each individual body part are determined by numerous genes.
Although you don't necessarily have to major in interior design, a bachelor's degree or higher in the discipline provides the best foundation for a career, according to the Foundation for Interior Design Education and Research.
A college degree is not always required to be an interior design consultant. If you work as a wholesale or sales representative, you only need a high school, according to the BLS. However, as seen in October 2011 job postings on Monster.com, employers prefer some coursework be taken in the design field.