The answer is "all of the above".
Genes are responsible for inherited traits. They are units of coded DNA which are located in a specific place on a chromosome. Genes are the basic unit of heredity, both physical and functional. Genes vary in size in humans, it comes in a few hundred DNA bases to 2 million more. It has been estimated by the Human Genome Project that humans have 20, 000 and 25, 000 genes in between.