What is more influential, nature or nurture? How can scientists know for sure? In this lesson, we’ll look at studies designed to separate the effects of genetics and environment on people’s behavior, twin and adoption studies.
Eric is interested in why people become addicted to drugs and alcohol. He’s heard that a lot of times, children of addicts become addicts themselves. So does that mean that it’s something that’s inherited, like brown hair or freckles?Eric is interested in the impact of genetics, or inherited traits, on people’s behavior. This is something that psychological research often tries to answer. But it’s a very complicated question and one that Eric won’t find an easy answer to!Let’s look at why genetic research is complicated and two types of studies that attempt to figure out how genetics influence our behavior, twin studies and adoption studies.
Nature vs. Nurture
So Eric wants to figure out why people become addicts. He knows that children of addicts often become addicts themselves, so he thinks that it could be genetic, like the color of someone’s eyes or how tall they will become.
In order to show that a person’s genes are what make them an addict, Eric figures that he should just find a bunch of addicts whose parents are also addicts. After all, if a parent has red hair and their child has red hair, then we say that red hair is genetic. It should work the same way with addiction, right?Not so fast! Unlike red hair, addiction can be influenced by many different things. Let’s imagine that Eric studies an alcoholic and discovers that her father was also an alcoholic. Does that mean that she inherited a gene that made her an alcoholic? Or did she become an alcoholic because she was raised in an environment where alcoholism was normal?These questions tap into a debate in psychology.
Sometimes referred to as nature versus nurture, this debate tries to figure out whether behavior is more influenced by genetics or environment. A person’s nature is their genetic makeup, while their nurture is their environment, or how they are nurtured within that environment.As with Eric’s subject, the answer isn’t always easy to figure out. In reality, both nature and nurture influence our behavior. But the question is how much influence do each of them have on us?
Eric really wants to figure out what’s going on with addiction and genetics. Is addiction all a product of a person’s environment? Is it all genetic? Or, like most things, is it a combination?As we’ve seen, studying nature and nurture can be complicated. There’s no way for Eric to know if his subject is an alcoholic because she inherited the genes for it, or because she was raised in an alcoholic household, or if it’s a combination of the two.
There are a couple of ways that Eric can study the effects that nature and nurture have on a person. One popular type of study is an adoption study, which compares an adopted person’s behaviors to those of their biological parents and their adoptive parents.Let’s go back to Eric’s subject. Her father was an alcoholic, and now she is, too.
There’s no way for Eric to know if that’s due to her nature or her nurture. But imagine for a moment if the subject had been adopted when she was a baby and raised by parents who didn’t drink alcohol at all. If she became an alcoholic as an adult, Eric might conclude that there’s some sort of genetic influence on alcoholism.Why would he guess that? In an adoption study, if a person is more like their biological parents, the likelihood of there being a genetic component is high. Their genes, which they share in common with their parents, are helping to shape their behavior. On the other hand, if a person in an adoption study ends up more like their adoptive parents, the environment is probably shaping their behavior more. After all, the environment is what they share with their adoptive parents, not genes.
So, if Eric’s subject is adopted as a baby and ends up in a family of teetotalers, and the subject grows up not to be an alcoholic, then Eric might believe that alcoholism is mostly due to the environment, not genes. But if she ends up an alcoholic even though she’s raised by people who don’t drink, then he might conclude that her genes are influencing her behavior.
As we’ve seen, figuring out how much influence nature, or genetics, has on a person versus how much influence nurture, or environment, has on a person can be complicated. And even if Eric does an adoption study, he might not fully be able to answer that question.
After all, even if his subject is brought up by parents who don’t drink, there are many other parts of her environment that could lead her to alcoholism. For example, perhaps she ends up friends with people who are alcoholics. Their environmental influence could have as much an effect as her biological father’s alcoholic genes.So what’s Eric to do? Another type of study that he could conduct is called a twin study.
This involves studying behaviors of identical twins to figure out how much of behavior is affected by genes. For example, imagine that Eric’s subject is the daughter of an alcoholic, and she becomes an alcoholic herself. But it’s hard for Eric to know if she’s an alcoholic because of the genes she inherited from her father or because she was raised in the house with her alcoholic father.But now let’s imagine that she has an identical twin sister. Unlike other family members, identical twins have the exact same genes, so if something is genetic, you’d expect both of them to have it.Let’s say that Eric’s subject is an alcoholic, but her identical twin sister is not an alcoholic. Then Eric can conclude that it is the environment, not genetics, that is causing her alcoholism.
After all, if it was her genes, her sister would be alcoholic, too, since they have the same genes.Some twin studies are also adoption studies. For example, Eric could study two identical twins who were raised in different households. The things that they have in common he would likely attribute to genetics, while the things that are different are likely more influenced by environment.
A person’s genetics can have a powerful influence on their behavior.
However, an ongoing debate in psychology is the nature versus nurture debate, which looks at whether a person’s nature, or genetics, is more or less influential on their behavior than their nurture, or environment. Because of the complex interaction of nature and nurture, it can be difficult to determine how they each influence behavior. One way to examine the effects of genetics on behavior is through an adoption study, which compares the behaviors of adopted people to their biological and adoptive parents. Another type of study that examines genetics is a twin study, which compares the behaviors of identical twins.
You will have the ability to do the following after watching this video lesson:
- Describe the nature versus nurture debate
- Explain how adoption and twin studies can be used to examine the interaction of nature versus nurture