Based on genetic studies, scientists estimate that 30% to 60% of your personality is inheritable. Research also suggests that significant personality changes tend to occur between ages 20 to 40.

Were you born this way, or are you a byproduct of your environment? The notion of nature versus nurture is an enduring debate that so far, no scientist or philosopher has been able to definitively answer.

While some studies show that a large portion of your personality is heritable, the exact extent — including what types of traits are heritable — is still largely a mystery. But here’s what experts do know so far.

Is your personality inherited or learned? 

Some researchers defineTrusted Source personality traits as patterns of thoughts, feelings, and behaviors that differentiate one individual from another. However, others have definedTrusted Source personality traits as dispositions “essentially independent of environmental influences,” which, by definition, rules out a “learned” component.

For the sake of this article, we’ll refer to the first definition.

According to a 2018 reviewTrusted Source of several twin and adoption studies, human personality is estimated to be 30% to 60% heritable.

These studies compared the personality traits of identical twins, who share 100% of the same DNA and who were raised both together and apart. These studies consistently found that identical twins, even when raised in different environments, shared more personality traits in common than non-twin siblings or adopted children.

These studies specifically observed the “Big Five” personality traits, including:

• neuroticism
• extraversion
• openness to experience
• agreeableness
• conscientiousness

Researchers also specifically discovered 42 sets of genetic variations (associated with 727 specific areas in our DNA) that appear to be strongly linked to personality traits.

Of course, environmental factors like early childhood experiences and cultural influences appear to have a crucial role in shaping one’s personality.

For instance, children raised in adverse conditions, such as with neglect, abuse, or poverty, are typically found to be more impulsive. Scientists say this is because this environment “activates” impulsive temperament genes that may have otherwise been dormant.

Meanwhile, those raised in healthy, nurturing, safe environments are more likely to have calmer temperaments because different genes are then activated.

That being said, since genomics is a relatively newTrusted Source area of scientific study, there’s still much to be learned.

At what age does a child develop their personality?

There’s no set age when a child develops their personality, which remains largely fluid throughout life. However, according to a 2020 reviewTrusted Source, one’s personality has roots in early temperament, which is observable as early as 4 months of age.

Temperament consists of two core parts: reactivity, or emotional responses, and self-regulation, or the ability to control these responses.

For instance, an infant who shows significant limb movement when shown a toy is considered highly reactive, scientists say. If that infant smiles and vocalizes, then the infant is considered high in positive affect, which is linked to the personality trait of extraversion.

However, scientists note that the link between temperament and personality is rarely strong. So for instance, an introverted child may also be very high in positive affect later in life.

According to an older review from 2008Trusted Source, personality traits continue to change throughout childhood and adulthood, particularly between ages 20 to 40.

What personality traits are heritable?

Since much of DNA remains a mystery, scientists are just scratching the surface of determining which personality traits can definitively be passed down.

According to the National Library of Medicine (NIH), there are certain gene variants that appear to be linked to temperament in particular, including:

• DRD2 and DRD4 gene variants, linked to a desire to seek out novel experiences
• KATNAL2 gene variants, associated with discipline and caution
• PCDH15 and WSCD2 gene variants, associated with sociability
• MAOA gene, linked to introversion (especially in certain contexts)
• AGBL2, BAIAP2, CELF4, L3MBTL2, LINGO2, XKR6, ZC3H7B, OLFM4, MEF2C, and TMEM161B gene variants are linked to anxiety and depression

Keep in mind that while some studiesTrusted Source have found that extraversion, agreeableness, and conscientiousness have significant heritability, other studies have found the opposite.

According to a 2015 studyTrusted Source, traits like openness to experience and neuroticism appear to have an estimated 15% heritability.

In a 2018 reviewTrusted Source, researchers note that traits like self-directedness, cooperativeness, and self-transcendenceTrusted Source, which are considered to be traits strongly linked to one’s health, are estimated to be 50% to 58% heritableTrusted Source

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