A River of Humanity
The genotype is the genetic composition of an organism, our DNA, responsible for particular traits. The phenotype determines the physical appearance of an organism. The DNA is composed of single nucleotide polymorphisms (SNPs) that represent biological diversity. A difference in a single DNA basic pair, represented by one of four molecules adenine (A), thymine (T), guanine (G), and cytosine (C) changes a trait. A heritability of 40% or 50% for any one trait means that percentage of the difference, between individuals, which can be attributed to differences between them in an inherited DNA sequence. Height and weight and intelligence are examples of traits.