Final answer:
Two main factors, genetic factors and environmental factors, govern a trait. Genetic factors are based on the alleles inherited from parents, as explained by Mendel's Law of Segregation, while environmental factors can significantly influence the expression of these genetic traits.
Step-by-step explanation:
The two factors that govern a trait are genetic factors and environmental factors. Genetic factors pertain to the hereditary information contained within genes and their alleles. For instance, alleles determine attributes like eye color, height, and certain personality traits through their dominant and recessive interactions. Mendel's Law of Segregation explains that each organism has two alleles for each trait, which segregate during gamete formation, ensuring offspring inherit one allele from each parent.
Environmental factors play a substantial role in the expression of traits as well. They can influence the observable characteristics, or phenotypes, through interactions with an organism’s genetic makeup. For example, exposure to the sun can darken the skin, and in some species, like reptiles, environmental conditions like temperature can even determine the sex of the offspring.
In summary, while each parent provides only one allele for each trait to their offspring, the expression of these traits is also significantly influenced by the environment. This creates a complex relationship between genetics and the environment, shaping both an organism's genotype and its phenotype.