There is biological variation in the human species—with traits such as blood type, genetic diseases, cranial features, facial features, organ systems, eye color, hair color and texture, height and build, and skin color varying across the globe. The typical height of an adult human is between , although this varies significantly depending on sex, ethnic origin, and family bloodlines. Body size is partly determined by genes and is also significantly influenced by environmental factors such as diet, exercise, and sleep patterns. Adult height for each sex in a particular ethnic group approximately follows a normal distribution.