An individual's height is determined by many genes.

Most hereditary traits are determined by more than one gene. These include traits such as height, skin colour, intelligence and musicality. For example, skin colour is affected by at least four alleles in different chromosomes.

The expression of genes in an organism can be influenced by their environment. Here, too, human height is a good example. Genes that influence the individual's height are inherited from its parents, but nutrition and the amount of sleep can affect the individual’s final height. Similarly, the individual's environment and experiences have a significant impact on their intelligence.

Genes also affect other human mental traits. An individual's personality is formed in the brain, and the individual's genes direct their brain development.