Final answer:
While individuals have two alleles for a gene, multiple alleles exist at the population level, contributing to genetic diversity. The most common version in a population is called the wild type, and variations to it are considered mutants, which can be either recessive or dominant.
Step-by-step explanation:
Do most genes in a population have more than just two alleles? The answer is that individual humans, and all diploid organisms, are limited to having two alleles for a given gene; one from each parent. However, across a population, many combinations of two alleles are observed due to the presence of multiple alleles for the same gene.
This genetic variety contributes to the diversity in a species. For example, the human ABO blood type is determined by three different alleles: IA, IB, and i. The convention is to call the most commonly observed version in a population the wild type, which is often labeled with a '+' sign.
Variants, or mutations, that occur are considered different from this wild type and can be either recessive or dominant to it.