Developmental Psychology

passed on to other children. Genes that interact with one another is called the gene-gene interaction and they can also interact with their environment called the gene-environment interaction . Let’s look at the gene-gene interactions. Gene-Gene Interaction • Additive : This shows the contribution of multiple genes o For example : A woman who is tall has a child with a man who is short, and the child is a medium height. • Dominant-Recessive: These genes are known to be non-additive, meaning they are a one or another. o For example: A person who has a dominant gene for brown eyes, can be a carrier for blue eyes. Brown eyes are typically shown since they are the dominant gene. • Incomplete Dominance: This is a phenotype that is not completely controlled by the genotype. o For example: Some red flowers and white flowers may produce punk flowers with a variety of hues that are pink. • X-Linked Genes: These are the genes that are on the X chromosome and can be dominant or recessive and happen to be more common in men. o For example: Baldness in men is carried on the X chromosome. Gene-Environment Interactions A person’s environment can have unpredictable effects on genetics. Studying identical twins especially, but other types of twins helps researchers understand how particular environments can impact genetics. Identical twins or monozygotic happens when one of the fertilized zygotes splits and creates two identical clusters of cells, that do fully develop. Identical twins do have identical genes. Fraternal twins do not have identical genes and are no different than brothers and sisters who are born during different pregnancies. The assumption that monozygotic twins are the same as dizygotic twins is not always the case. Studying twins who were separated at birth is usually the easiest method to test these assumptions. Studying adopted children by looking at the traits of the adopted parents and not biological parents may indicate if there is a particular trait that is genetically based or environmentally based. (Here is nature vs nurture again) Natural S lection Charles Darwin proposed the theory of natural selection. Natural selection is known for its influence deciding which genes are expressed at a given time. Natural selection says that when organisms have the highest ability to survive and pass genes on to the next generation, is when they have adapted strongly to an environment. Charles Darwin created a study with Galapago finches when he wanted to study natural selection. Darwin observed different finches on different individualized islands. The different finches slightly varied from one another. Some had short beaks, while others had long ones. After he observed the finches for a while, he had concluded that the beak size and the beak shape varied on the type of food that was available on the island. Although the finch was stemming from its common ancestor, it had adapted to its environment and developed into a new species that allowed them to reproduce and to survive in its new environment or environment.

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