Pedigrees

A pedigree is a diagram that shows the genetic relationships among family members and traces the inheritance of specific traits.

A square represents a male in a pedigree.

A circle represents a female in a pedigree.

It often indicates that the trait is recessive, meaning individuals can be carriers without expressing the trait.

A dominant allele is an allele that expresses its trait even when only one copy is present in the genotype.

A recessive allele is an allele that only expresses its trait when two copies are present in the genotype.

A heterozygous genotype has two different alleles for a trait, such as 'Gg'.

A homozygous genotype has two identical alleles for a trait, such as 'GG' or 'gg'.

We use pedigrees to track traits in families and make determinations about the inheritance of those traits.

A carrier is an individual who has one copy of a recessive allele and does not express the trait but can pass it on to offspring.