How Are We Genetically Related?

Author: Belinda Lin

Editors: Vincent Chang and Kira Tian

Artists: Gianluca Zhang

People are made up of characteristics carried down from their ancestors—characteristics that are made both genetically and physically. A genotype refers to the genetic component of their DNA while a phenotype refers to the physical component of an individual. Genotypes and phenotypes are correlated, as a change in one’s genotype can influence one’s phenotype.

Genotypes are the genetic characteristics of a person. They encode the color or shape of a specific trait (height, hair color, wingspan, eye color, etc). Genes can occur in different forms, known as alleles, across organisms. Humans inherit two copies of the same allele or two copies of different alleles from a parent. If an individual inherits two copies of the same allele, the genotype at its locus is considered homozygous. A homozygous locus can either be dominant or recessive. A dominant allele is a feature that the majority of the human population has. For example, a person with brown eyes has dominant alleles in contrast to someone with blue eyes who has recessive alleles. To get blue eyes, in this case, one would need two recessive alleles, On the other hand, if someone inherits two different alleles, the locus is considered heterozygous. Inheriting two different alleles expresses a dominant and hides the recessive allele. Consequently, having one dominant trait and one recessive, the dominant allele will be expressed over the recessive trait.

A phenotype, however, is an observable characteristic that is not inherited from a parent. These factors can also be determined by the difference in DNA sequences. These traits are encoded by genes that enhance specific behaviors or features. However, scientists have concluded that environmental factors play a bigger role in phenotypes. For example, the type of food people eat or how they exercise, or whether or not they smoke can all cause a change in eye color or pigmentation. The shape of a bird's wing and the calls of a humpback whale are some of the characteristics that are considered phenotypes.

Much of human history comes from past generations of DNA. Understanding how genes work and the reasons for these specific features are equally important to find out about the past. Genotypes are the genetic encoding of the DNA sequence from previous generations while phenotypes are alterations in the DNA sequence from a surrounding environment.

Citations:

“What Is the Difference between a Genotype and a Phenotype?: Jain Foundation.” What Is

the Difference between a Genotype and a Phenotype? | Jain Foundation, www.jain-

foundation.org/what-difference-between-genotype-and-phenotype#:~:text=A%

20genotype%20refers%20to%20the,brown%20eyes%20is20genotype%20a%.

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