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.
For those states that do require this, the National Council for Interior Design Qualification administers the exam. Applicants must have six years of combined education and interior design training, including two years of postsecondary education, to be eligible to take the test. Each state has its own interior design requirements for continuing education.