Hereditary vs. Genetic: How Genetics Differs from Heredity
Do the two terms truly differ from one another? And, if they do, how so? Up until now, you may have assumed that the two words are perfectly interchangeable as they have largely been treated as synonyms in several disciplines, particularly in the life sciences. Not only are the two used in the same context, they are treated as completely interchangeable.
Technically, however, this is not the case. The two words “genetic” and “hereditary” are indeed different and ought to be treated as such. Using them interchangeably to mean one and the same thing will not get you in trouble but it might lead to confusions.
For the most part, a hereditary trait or feature is also genetic in nature. However, there are also instances in which a trait or feature is genetic and not hereditary. And, yet there are also situations in which a trait is hereditary without being genetic. So, what about things like ovarian cancer, breast cancer, pancreatic cancer, prostate cancer, Alzheimer’s disease, alcohol use disorder, dimples, and so on. Are these genetic diseases or hereditary? Which ones will put you at higher risk?
OK, so what is a genetic disease? A genetic disease is a condition that occurs as a result of a mutation or an anomaly in an individual’s genome. Genetic diseases, while they may or may not be hereditary, will always be the result of a mutation. However, hereditary diseases, which are health conditions that are also caused by genetic mutations that have the potential of being passed down a line of generations. Diseases such as Down syndrome, spherocytosis, Achondroplasia, Hemophilia, sickle cell anemia, muscular dystrophy, Turner syndrome, Albinism,and Galactosemia are examples of hereditary diseases.
Let’s bring up another example. If we analyze a trait that has been passed on for generations that trait is typically termed as either genetic or hereditary. By virtue of that trait, feature or characteristic being passed down the lineage of generations, we assume that it is linked to genes or the genetic makeup of the organisms. However, that is not always the case, which is why using both terms equally are not always safe. (Sure, there is a fine line between the two terms, but as fine as it may be, it is still there, making the two terms different.
So, what, exactly, is the difference between genetic and hereditary diseases? If we define genes as matter that is present in the body whose role is to transmit traits from parents to offspring across generations, any change in the gene—or mutation—is also transmittable, making that change both genetic and hereditary. And, yes, it is true that there is a large overlap between the two terms. However, in the case of spontaneous or induced genetic mutations that can cause defective or faulty genetic material that may cause disease, it may not be hereditary at first but may become so if it is passed on across generations. The most crucial difference between the two terms is that a hereditary disease can be passed on from one generation to another. A genetic disease, on the other hand, may or may not be hereditary, but it is always a result of a change in an organism’s genome.
Let’s go back to non-genetic traits. These may also be passed on from generation to generation. And while these are not genetic in nature, they certainly are hereditary. Let’s take language, for example. The mother tongue is clearly passed on from generation to generation. By simple virtue of that, the spoken language is a trait that is hereditary and not genetic as it is acquired by speaking, listening, and interacting. There is no genetic backdrop to that. However, the linguistic capacity—one’s neurological capability to speak a language—is something completely different. This neurological capability is largely dependent on the biological neural network of a person and, therefore, does have a genetic component. Because of that, linguistic capacity can be termed to be both hereditary as well as genetic.
In fact, Richard Dawkins’ commentary in The Selfish Gene is spoton:
“Cultural transmission is analogous to genetic transmission in that, although basically conservative, it can give rise to a form of evolution. Geoffrey Chaucer could not hold a conversation with a modern Englishman, even though they are linked to each other by an unbroken chain of some twenty generations of Englishmen, each of whom could speak to his immediate neighbours in the chain as a son speaks to his father. Language seems to ‘evolve’ by non-genetic means, and at a rate which is orders of magnitude faster than genetic evolution…”
The line between genetic and hereditary may be fine, but it is important. This is particularly true for traits that are hereditary and not genetic as they are helpful in efforts to understand certain human behavior. This is the case with pathological characteristics as they pertain to the understanding of mental disorders. By virtue of believing that mental disorders are largely genetic without a hereditary aspect, the whole part about hereditary transmitted dysfunctional behaviors can be overlooked. For example, children who grow up in happy households will—for the most part—grow up to be happy by virtue of their parents being happy. On the other hand, children who grow up in households whose parents are anxious, they will pass on those traits to their children. These two examples do not mean that there is a “happy gene” or “anxiety gene.” There might be, but we must be careful not to use the term genetic as an umbrella term for everything that is passed on from parents to offspring.
Ultimately, an organism’s majority of traits are also genetic. However, one must not assume that hereditary and genetic are synonymous. There are characteristics that are genetic without being hereditary and vice versa. There are traits that are hereditary without a genetic backdrop or underpinning.
There you are. Now you can confidently discern the two terms and you’ll never use them interchangeably again, for the most part.