Dominant alleles show their effect even if the individual only has one copy of the allele (also known as being heterozygous^?). For example, the allele for brown eyes is dominant, therefore you only need one copy of the 'brown eye' allele to have brown eyes (although, with two copies you will still have brown eyes).

Do dominant traits always show?

1) If a person shows a trait that is dominant then at least one of their parents must always show the trait. This rule comes from the fact that the dominant allele always wins.

What does a dominant trait tell us?

A dominant gene, or a dominant version of a gene, is a particular variant of a gene, which for a variety of reasons, expresses itself more strongly all by itself than any other version of the gene which the person is carrying, and, in this case, the recessive.