Sources of Biological Abnormalities: Genetics & Evolution

An error occurred trying to load this video.

Try refreshing the page, or contact customer support.

Coming up next: Biological Treatments for Psychological Abnormalities

You're on a roll. Keep up the good work!

Take Quiz Watch Next Lesson
Your next lesson will play in 10 seconds
  • 0:06 Biological Model
  • 1:36 Genetics
  • 3:25 Evolution
  • 5:48 Lesson Summary
Save Save Save

Want to watch this again later?

Log in or sign up to add this lesson to a Custom Course.

Log in or Sign up

Speed Speed

Recommended Lessons and Courses for You

Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

There are many factors that can affect a person's mental health. How do elements like genetics and evolution play a role in psychology? In this lesson, we'll look closer at how genetics and evolution can affect mental illness.

Biological Model

Chris is different from other people. He doesn't feel emotions very strongly and has very little empathy for others. He has committed several serious crimes and shows no remorse for them. It's like he doesn't care about anyone but himself. Chris is suffering from antisocial personality disorder, a psychological disorder that involves disregard for others' rights.

Antisocial personality disorder is one of many mental illnesses studied by psychologists in abnormal psychology. The psychological community does not agree, however, on the cause of mental illnesses. Take Chris for example. Some psychologists might say that his antisocial personality disorder springs from unresolved issues in his childhood. Others believe that it is caused by learning bad behaviors.

The biological model of abnormal psychology says that psychological disorders are caused by biological anomalies. In Chris' example, the areas of his brain responsible for emotion might be damaged or not working as well as in healthy adults.

In fact, there is evidence that the brains of people with antisocial personality disorder work differently than those in people who do not have a mental illness. But, if biological abnormalities are the problem, what causes those? In this lesson, we'll look at two sources of biological anomalies: genetics and evolution.


Chris is adopted and was raised in a happy home. And yet, he has antisocial personality disorder. When he looked up his biological parents as an adult, he found out that his father also had antisocial personality disorder. What's going on?

Genes are the building block of human life. A person's genes can influence all sorts of things, from what color eyes they have to whether they develop a mental disorder. There are many psychological disorders that are influenced by genetics, including schizophrenia, bipolar disorder, Alzheimer's disease, and anxiety disorders. Of course, genetics are not the only cause, but they can have a powerful impact.

Psychologists study the relationship between genes and mental health in several ways. One type of genetic study is a twin study. Since identical twins have exactly the same genes and fraternal twins have about half their genes in common, it's helpful to look at the prevalence of mental illness in twins. If something is 100% caused by genetics, someone with an identical twin who has a disorder will also have that disorder.

Of course, nothing is 100% caused by genetics, and our environment also has an impact on who we are. To study the impact of both genes and environment, psychologists run adoption studies. Remember Chris? He has the same psychological disorder as his biological father. In that way, we know that his disorder has a genetic component. If, on the other hand, his biological father was healthy but his adopted father had antisocial personality disorder, we would know that the environment likely plays a larger role than genetics.


Our genetics influence our biology, but what influences our genes? According to Charles Darwin, the genes that you and I have are a result of evolution. His theory says that genes that help a person survive and thrive are passed down because those who are strong end up having children.

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account