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An overview of how traits are passed from parents to offspring and the difference between inherited and acquired traits.
Have you ever wondered why you have your mother's eyes or your father's sneeze, yet neither of them can play the guitar as well as you do?
Heredity is the biological process where parents pass certain genes onto their children or offspring. Every child inherits genes from both of their biological parents, and these genes express specific traits. Genetics is the scientific study of heredity—it is the field of biology that seeks to understand how these characteristics are transmitted through generations. Think of heredity as the 'delivery' of traits, while genetics is the 'instruction manual' that explains how those traits are built. In humans, the probability of inheriting a specific trait can often be calculated using mathematical models, where the chance of an offspring having a trait depends on the parental genotypes.
Quick Check
If a scientist is specifically studying the chemical structure of DNA to see how it stores information, are they practicing heredity or genetics?
Answer
Genetics, because they are studying the scientific mechanism and 'instruction manual' of how traits work.
Inherited traits are characteristics that are coded in your and passed from parents to offspring. These are traits you are born with. In humans, this includes physical features like eye color, hair texture, skin tone, and even some internal features like blood type. In the plant world, this might include the shape of a leaf or the color of a flower. These traits are fixed at birth and do not change based on your environment or effort. For example, if both parents have the genotype for a specific trait, the probability of the offspring expressing that trait can be represented as a ratio, such as or .
Consider the trait of a 'cleft chin' (a small dimple in the chin). 1. Parent A has a cleft chin (Genotype ). 2. Parent B does not have a cleft chin (Genotype ). 3. The offspring has a chance of inheriting the cleft chin. 4. Because this is coded in the , the child is born with this trait; they did not 'learn' to have a dimple.
Not everything about you comes from your parents' genes. Acquired traits are physical characteristics that an organism develops during its lifetime due to environmental influence or lifestyle. For example, a scar from a bicycle accident or large muscles from weightlifting are acquired. Similarly, learned behaviors are actions developed through experience or practice, such as speaking a specific language or playing a sport. These traits are NOT passed down to the next generation because they do not change the information in your cells (gametes).
Imagine a world-class professional athlete who has spent 20 years training. 1. The athlete has developed incredible lung capacity and muscle density (Acquired Traits). 2. The athlete knows exactly how to perform a complex gymnastics routine (Learned Behavior). 3. If this athlete has a child, the child will NOT be born with large muscles or the knowledge of gymnastics. 4. The child only inherits the potential for athleticism, not the results of the parent's hard work.
Quick Check
A dog is taught to 'sit' on command. Is this an inherited trait or a learned behavior?
Answer
It is a learned behavior because the dog was not born knowing the command; it was acquired through training.
Consider a sun-tanned person who is also naturally very tall. 1. Height is an inherited trait determined by , though it can be influenced slightly by nutrition. 2. A sun-tan is an acquired trait caused by the skin's reaction to radiation from the environment. 3. If this person has a child in a room with no sunlight, the child will likely be tall (inherited) but will not be born with a tan (acquired).
Which of the following is an inherited trait?
Why are acquired traits NOT passed from parents to offspring?
Genetics is the study of how traits are passed from one generation to the next.
Review Tomorrow
In 24 hours, try to list three physical traits you have that are inherited and three skills you have that are learned behaviors.
Practice Activity
Look at a family photo. Identify one trait you share with a parent (inherited) and one hobby you both enjoy (learned behavior).