The passing of traits from parents to a child is called heredity. Humans have 2 sets of traits, each set containing 23 chromosomes. An egg cell contains one set of chromosomes, while the sperm cell contains the other set of chromosomes. When the egg and sperm combine, they create a cell called zygote, which has two sets of chromosomes, half from the mother and the other half form the father.
A trait is a notable feature or quality in a person. Physical traits are characteristics of one's physical makeup such as hair color, eye color, and height. Behavioral traits are characteristics of the way one acts. An increased risk of getting a certain kind of health problem is also a trait that could be passed on to a child from a parent. Environmental factors can influence or change traits. A set of genetic information for each form is described as an allele. Homozygous is when you have two of the same allele for a trait. Heterozygous is when you have two different alleles for a trait. Traits are usually shaped by more than one gene; this called complex traits.