Is Agreeableness Genetic? How Genes Impact Interpersonal Relationships

If you can’t help but wonder why a certain coworker is always so warm, cooperative and kind, or maybe why certain siblings are more empathetic than others, then you’re not alone.

Often, we find ourselves trying to understand why people’s personalities are the way they are – and agreeableness as a personality trait is no exception.

For years, psychologists have tried to pin down whether agreeableness is genetic, a learned trait, or both. In this article, we dive into the science behind how agreeableness is formed, and take a deep look at whether it’s formed by nature or nurture.

While research suggests that agreeableness is genetic to some extent, the effect of environmental factors is also evident.

Nature vs. Nurture: A Brief Overview

While nature refers to what we believe to be pre-wired or genetically inherited, nurture depicts the impact on an individual from external, postnatal factors, such as life experiences and relationships.

The debate between nature and nurture begs the question: Are personality traits, or in fact behavior in general, learned from individual life experiences or are they predetermined by genetic factors?

Those who take the view of Nativism tend to follow the biological approach to psychology whereby behavior is explained through biological factors such as genetics, hormones, and neurochemicals.

Someone taking an Empiricist stance (believing nurture to be responsible), on the other hand, would claim that human experience plays a more fundamental role in behavior and, ultimately, personality.

So, what evidence do we have that agreeableness is genetic?

Is Agreeableness Genetic?

This question has a more complicated answer than just yes or no, as is often the case with nature vs. nurture conundrums. While the extent of agreeableness can be influenced by external factors, some people are more prone to the personality trait than others.

First, let’s look at some of the research around the influence of genetics on agreeableness.

How Nature Affects Agreeableness

Researchers have found that several variants of the DRD3 gene correlate with agreeableness. This gene is found in the limbic system, the area of the brain responsible for controlling many human behaviors.

This finding suggests that agreeableness levels fluctuate depending on whether specific gene variants are present, revealing a genetic influence on agreeableness.

Further research has also identified a significant relationship between agreeableness and the CLOCK gene. This gene has a fundamental function in driving circadian rhythms, a 24-hour cycle of physical, mental, and behavioral changes all humans possess. The CLOCK gene is believed to impact physical and behavioral rhythms specifically.

This finding suggests that agreeableness levels fluctuate depending on whether specific gene variants are present.

This, in turn, highlights a genetic influence on agreeableness. But is this supported by all? Simply put, no.

Agreeableness & Genetics in Twins

Studies analyzing agreeableness in adoption and twins found that genetic influences only accounted for 12% of the variance in agreeableness between twins. They also found that a shared rearing environment accounted for 21% of the variance.

This suggests that environmental factors have a more significant influence on agreeableness than genetics.

Another twin study, conducted in 1996, looked at the genetic and environmental influence on six agreeableness facets: Compliance, tenderness, modesty, trust, straightforwardness, and altruism.

They found a 30%, 47%, and 34% genetic influence on trust, straightforwardness, and altruism, respectively.

However, there was no significant genetic effect on modesty. Furthermore, the genetic components were primarily nonadditive for compliance and tenderness, meaning there was barely any genetic effect on the personality trait of modesty.

So, if genetics isn’t the only factor affecting the extent of agreeableness, what other elements are at play?

How Nurture Affects Agreeableness

There are several environmental factors believed to influence a person’s level of agreeableness, including:

• Age
• Parenting style
• Gender

First, let’s look at age.

Age

Evidence suggests that agreeableness typically increases with age. In fact, many personality changes occur as you grow older. This phenomenon is called the maturity principle.

The maturity principle highlights the impact of social factors on personality. It suggests that a person’s personality changes as their priorities change throughout life (for example, from independence to seeking a romantic partner to creating a family).

Parenting Style

Parenting style also seems to impact agreeableness. An angry, restrictive, and controlling parenting style, particularly in mothers, produces less agreeable offspring.

Meanwhile, positive parenting (characterized by warmth and low psychological control) results in children with higher agreeableness scores.

Gender

Women typically rate higher on agreeableness than do men. This was demonstrated in a 2001 study which found that college-age and adult women rated themselves higher in agreeableness on the NEO Personality Inventory than did men.

Bottom Line

The trusting and positive outlook on life of those scoring high on agreeability can certainly be important in life and considered enviable by some. But even if you’re not agreeable now, you still can become agreeable in the future.

While genetics appears to have a hand in the extent of a person’s agreeableness, it’s not the only influential factor. In actuality, agreeableness is highly malleable and affected by various external stimuli, including age, parenting/rearing environment, and gender.