While the exact number is debated, there are probably around 20,000 genes in the human genome. People generally have the same set of genes. The Y chromosome is carried only by men, but it is one of the smallest chromosomes and only has a few genes.
There can be a great deal of variation within the genes we carry, which is part of what gives rise to the individual physical and biological characteristics that people have. Some of those genetic variants, which are discussed in this video, are related to disease and may predispose us or protect us from certain disorders. Learn more about how researchers are trying to connect genetic variants and disease risk to improve health.