Question

what makes a trait dominant or recessive

Answer 1

A person possessing one dominant allele and one recessive allele for a gene is said to be heterozygous for that trait because the alleles are different. However, if a person possesses two alleles that are the same, such as two dominant alleles or two recessive alleles, then that person is homozygous for that trait.

Answer 2

Dominant refers to the relationship between two versions of a gene. Individuals receive two versions of each gene, known as alleles, from each parent. If the alleles of a gene are different, one allele will be expressed; it is the dominant gene. The effect of the other allele, called recessive, is masked.