Why It Matters: Trait Inheritance

Why complete monohybrid and dihybrid crosses and family pedigrees, and explain the inheritance of various traits?

Take a moment to pause and think about yourself and your family. How much do you look like your parents? What about the other members of your family: aunts, uncles, cousins, full siblings, half-siblings? Why do some family members look nearly identical to each other, while other family members seem as if they don’t share two traits? The answer to this boils down to how traits are inherited.

Parents pass on traits to their children. Traits like blood type, cleft chin, dimples, and widow’s peaks are all inherited in a fairly straight-forward, simple fashion. However, the inheritance of other traits is much more complex and harder to understand: these traits include height, skin color, and eye color. These more complex paths of inheritance are what cause some siblings to look so different from each other—despite having the same two parents.

Unfortunately, genetics also plays a role in the inheritance of some diseases such as Huntingdon’s, sickle cell anemia, and Tay-Sachs disease. A degree in genetics can be used in careers ranging from a forensic examiner, a genetic counselor, a medical geneticist, a statistical geneticist, to a clinical technician.

Occupation Spotlight: Genetic Counselors

Genetic counselors use their understanding of the rules of heredity to help gauge the risks of genetic diseases. They may advise a couple of their risks for passing on certain genetic disorders, order genetic testing, and then explain the chances that some genetic diseases will show up in any offspring. Genetic counselors are there to help potential parents understand risk factors and the prognosis of genetic disorders, including basic treatment and management plans in the case of certain disorders.

Learning Outcomes

  • Identify the impact of Gregor Mendel on the field of genetics and apply Mendel’s two laws of genetics
  • Explain complications to the phenotypic expression of genotype, including mutations
  • Explain the conventions of a family pedigree and predict whether a disease will be passed through a family in one of three modes
  • Discuss the role environment plays on phenotypes