Examples of Heterozygous Traits

Genetics get a bit more complicated when it comes to heterozygous, or “different genetic” traits. Offspring who receive a dominant allele from one parent and a recessive allele from the other parent will exhibit heterozygous traits. That’s why siblings with the same parents sometimes look very different from each other: they received different combinations of genes.

Here are some examples of how offspring can exhibit heterozygous traits:

  • A parent provides the dominant allele for black hair (B), and the other parent provides the recessive allele for blonde hair (b). The offspring has black hair (Bb) because they exhibit the dominant gene only.
  • One parent has two dominant alleles for type A (AA) blood, and the other parent has one dominant allele (B) and one recessive allele (o) for type B (Bo) blood. One child has type AB (AB) blood but their sibling has type A blood (Ao) because they received one dominant A allele and one recessive O allele.
  • A litter of puppies with a Golden Retriever mother and a Great Dane father exhibit a variety of traits. Some puppies have shorter legs from their mother’s recessive alleles, while others are very tall because of their father’s dominant alleles.
  • One parent is a carrier for a genetic mutation on a dominant allele (Dd), but the other parent only has recessive alleles for that chromosome (dd). The child receives one recessive allele from each parent (dd) and neither carries nor exhibits the genetic disorder.
  • Two flowers with ten petals but different genotypes (PP and Pp) produce seeds for flowers with the dominant allele for ten petals and flowers with the recessive allele for nine petals.
  • One parent has poor eyesight (ee), but the other has a dominant allele for strong eyesight (Ee). Their offspring range in eyesight ability (ee and Ee).

As you can see, heterozygous traits allow for greater genetic variation. They can also protect offspring from gene mutation and possibly harmful genetic disorders. The alleles that offspring receives from its parents can determine what happens to its genetic line for generations to come.