Biological Predispositions: Definition & Concept

Instructor: Devin Kowalczyk

Devin has taught psychology and has a master's degree in clinical forensic psychology. He is working on his PhD.

Biological predisposition is commonly known as someone's 'nature', as opposed to their 'nurture', or upbringing. In this article, you'll be studying this concept and then testing your knowledge with a quiz.

The Future is in the Past

Biological predisposition is when a subject (human, animal, plant) possesses some internal quality that gives them an increased likelihood of having a condition. This is a technical definition, and what it's saying is this living thing has a higher probability to have condition X, Y, or Z. The title of the section alludes to a quality in something's past that will influence its future. Let's look at an example to see how biology can predispose someone.


Genes are molecular units for trait heritability. They're often made up of groups of DNA. DNA makes proteins, proteins make cells, cells make tissues, tissues make organs, and organs make up you. Many people like to point out that humans share 98% of their genes with chimpanzees. While this is mostly true, it should also be noted that humans share about 60% of the same DNA with banana plants. This means that a great deal of what genes do is fundamental, such as how to build cell walls and convert sugar to energy.


How It Works

Genes direct the production proteins, proteins make cells, cells make tissues, and tissues make organs. If your genes don't make enough of a particular type of neuron (a cell in your brain) or it doesn't function in just the right way, then you have a predisposition.

People who have difficulty with addictive substances have been found to have under-active reward centers in their brain. So when the addictive substance, like cocaine, is introduced, it's more pleasurable to them than to other people. This is what people say when they claim to have an addictive personality, or a sweet tooth.

When a person has a predisposition, they have an internal vulnerability to something. A genetic predisposition must be triggered by external stimuli. A person who is vulnerable to addiction who never takes cocaine can never be addicted to it. A person with a sweet tooth will never have an addiction to sweets if they never eat them. But that doesn't mean their risk for addiction is unimportant.


A person needs an external stimuli to help along a predisposition. Nowhere is this better seen than in schizophrenia. Schizophrenia affects about 1 in every 100 people. There is also an extremely strong genetic component. If your parent suffers from it, than your chances of having it are six times greater.

But what if your identical twin has schizophrenia? You and your identical twin have the same genes and you likely shared mostly the same environment. Your chances of also having schizophrenia are as high as 48%. This points to an extremely high genetic component, since those with similar genetics are more likely to get it. However, the environment also comes into play. Two people who shared nearly everything can still have different outcomes depending on their external environment and how they interpret it.

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