In This Article
In This Article
Traits are specific characteristics found in a person. They can be something physical and immediately observable, such as eye color, skin color, or hair color, or something more internal, like the ability to roll one’s tongue or cross the eyes.
These traits are shaped in part by genes and life experiences. In this article, we’ll simplify the science behind traits, clarifying how genetic factors interact with your environment to make you uniquely you.
Traits are predominantly determined by the following
Additionally, your traits can be determined by a mix of these factors. For example, if you're more extroverted due to your genes but grew up in an environment that “tones you down,” you might not be as outspoken as you can be.
Conversely, if you have a predisposition to anxiety and depression but are raised in a very supportive, loving family, it may not manifest as strongly.
These three terms are often confused with each other. While they're related, they all pertain to different things.
Here are their definitions:
Simply put, genes provide the blueprint, the allele has the instructions for the blueprint, and traits are the finished product. As the outcome of your genetic makeup, traits are what can be observed. You don’t have traits without the variant of a gene (the allele).
Your genotype is the genetic code inherited from your parents, while your phenotype refers to observable traits. Phenotypes include obvious characteristics like hair color and height, as well as measurable ones like blood type.
Everyday examples include:
Traits reflect the interaction between your genes and environment. Your genotype sets potential, and your environment influences how it's expressed.
Every offspring’s genes are made up of one allele from each parent. A gene is made up of two alleles, one from the mother and one from the father.
Alleles can be dominant or recessive within a pair. For example, between physical traits like brown eyes and blue eyes, brown eyes are the more dominant trait.
Suppose the allele pair has either dominant alleles or just one dominant and recessive allele; the dominant trait is expressed. Dominant traits are always expressed, even if there’s only one dominant allele.
It’s only when two recessive alleles are in a gene that the recessive trait is expressed. Recessive traits manifest due to the absence of a dominant one. However, some dominant alleles show incomplete penetrance, so the trait may not appear in every carrier.
Dominant alleles are usually denoted by capital letters, while recessive ones are denoted by non-capital letters for visual genetic representations, like Punnett squares. For example, the brown eye allele is often denoted as "R" while the blue eye allele is "r."
However, dominant traits aren't dominant in all pairs. Some dominant traits may not be dominant when paired with others, nor are they the only dominant trait.
Some of the most common dominant-recessive trait pairs in physical traits are (dominant on the left, recessive on the right):
Your traits don't just randomly appear—they follow specific patterns of genetic inheritance. Dominant traits, like brown eyes, typically overshadow recessive ones, such as blue eyes, when paired together.
Using a simple tool called a Punnett square, scientists visualize how these traits pass from parents to children.
Unlike simple traits, polygenic traits are influenced by multiple genes, resulting in a broad spectrum of outcomes rather than clear-cut categories. For example, skin color is influenced by multiple genes related to melanin production and levels.
Traits linked to chromosomes that aren’t sex chromosomes (autosomes) affect both sexes similarly, like lactose intolerance. In contrast, sex-linked traits like color blindness are associated with genes on sex chromosomes, usually affecting one gender disproportionately.
Yes, it's possible for traits you inherit not to manifest. Trait expression isn’t necessarily black-and-white; gene expression is more like a spectrum with different levels or intensities.
So, rather than an on or off switch for whether or not a trait will manifest, it may just not be as loud or noticeable as other traits.
For example, in a family that has curly hair, some may have more tightly coiled hair while others will have looser waves. All of this can be affected by your lifestyle, environment, and other factors like:
When parents have children, their genetic information is combined to create a unique new DNA structure in their offspring, which makes their children unique but with familiar features. This makes up their characteristics.
Parents contribute two alleles to each offspring’s genes. Certain features are expressed over others as traits depending on whether those alleles are dominant or recessive.
For example, if the father has curly hair, and it’s the dominant allele, and it gets passed down to a couple’s children, it will be more likely that the child will come out with curly hair even if their mother has straight hair.
A child can also inherit different traits from their parents which can be physical traits or behavioral characteristics.
Some people believe that natural selection has genetically empowered certain traits to protect our species and minimize the chances of us inheriting recessive traits, which may be considered less valuable to survival.
Genes that are considered important for survival and reproduction are often prioritized. "Harmful" genes have become more recessive due to evolution. This theory makes sense when you think of how many (but not all) harmful genetic variants are often recessive.
This goes for both physical and behavioral traits, as well as other genetic predispositions.
If you inherit two entirely different dominant traits, you may experience codominance. Codominance is when both traits are expressed without masking one another.
For example, the AB blood type is a combination of dominant blood type A and dominant blood type B. In incomplete dominance, the two traits blend as neither is masked.
You can observe this in many flowers. If a white flower and a red flower cross-pollinate, it's not always guaranteed that they will be either white or red.
In some cases, if the traits are codominant, the offspring will be pink or even have splotches of red and white. This is how people who cultivate flowers can develop specific colors.
People who share the same genes may share and exhibit similar traits, though they won't share all of them. Siblings will often have similar features or even dispositions, and some identical twins may also have similar personalities.
However, note that just because you share a substantial chunk of your genes, you won't be completely similar. Not even identical twins are totally alike.
This is because, despite having similar genes, your genetic sequences may still be totally different and manifest completely different traits. Each person has a unique set of genes, and certain traits will be expressed over others in varying degrees.
Traits are more than genetic code; they're your unique story shaped by biology and life. For personalized advice or to address concerns, consider talking to a professional. Learn more or speak with a genetic counselor to better understand your genetic profile.
