Have you ever wondered how close human beings really are to one another? Well you’d be surprised as to how alike we actually are. In fact, all humans are more than 99% identical. So no matter how different we look, we are closer than we think. All the differences we see amongst ourselves and other people make up for less than 1%. That includes eye colour, height, blood type; that we inherit from our parents.

According to Dr Ananya Mandal, “Genetics is the study of heredity. Heredity is a biological process whereby a parent passes certain genes onto their children or offspring.”

Identical twins have the same genetic makeup, but environmental factors, such as their upbringing or the state of their health, all influence their feature. Read more about this here.

What are genes?

Genes transfer the information that determines your traits, which are inherited from your parents. We inherit two copies of genes from our parents. These specific genes are called alleles and alleles are important because they shape the features of who we are.

Each cell in the body contains about 25 000 to 35 000 genes. So if both your parents have brown eyes, then you’ll most likely inherit brown eyes. Or if your dad is tall, then there is a chance that you might be pretty tall too.

How do genes work?

A cell reproduces by copying its genetic information then splitting in half, forming two individual cells. Occasionally, an alteration occurs in this process, causing a genetic change. When this happens, chemical messages sent to the cell may also change. This spontaneous genetic change can cause issues in the way the person’s body functions.

Every cell in the body, besides sperm and egg cells, are called somatic, which means ‘relating to the body’. Sperm and egg cells are called ‘germ’ cells.

So let’s say a change takes places in a person’s somatic cells, this individual may develop a condition that is related to that gene, but it won’t be passed on to that person’s kids. For instance, one can get skin cancer which causes changes in the genes of the skin cells, caused by the harsh UV radiation from the sun.

Changes in genes in the somatic cells includes exposure to chemicals and cigarette smoke. However, if the gene change occurs in a person’s germ cells, that person’s children have a chance of inheriting the altered gene.

Most cells have a single nucleus. The nucleus is the brain of the cell and it tells every part of the cell what to do. The nucleus contains chromosomes and genes.

Everyone at some stage in their life has learnt about chromosomes in biology class, or natural science as we South Africans call it. Better Health Channel perfectly describes how chromosomes work since we may need a bit of a reminder. “The chromosomes that determine the sex of the baby (X and Y chromosomes) are called sex chromosomes. Typically, the mother’s egg contributes an X chromosome, and the father’s sperm provides either an X or a Y chromosome. A person with an XX pairing of sex chromosomes is biologically female, while a person with an XY pairing is biologically male.”

Interesting gene facts

• All animals and plants have genes too and we are in fact quite similar to chimpanzees with 98%, mice with 90% and even flies with just over 50%.
• An interesting fact about DNA is that DNA molecules are incredibly long. If you took them apart and put them in one continuous line they would reach the sun and back, many times.
• The human body is incapable of living for longer than 120 years. This is due to genetic coding which has a limit to how times our cells can divide. The longest lifespan of someone, Jeanne Calment from France, has been documented at 122 years old (1875 – 1997).
• Many people don’t like the taste of cabbage or broccoli and other plants in that vegetable family because these vegetables contain chemicals similar to phenylthiocarbamide (PTC), which is a chemical that is tasteless or bitter depending on a person’s genetic makeup.

Why genetics is important for you

Getting to know your genetics can be crucial in terms of health. Your doctor would be able to use your family health history and the state of your current health to determine the risk of you developing a disease. If you know your family hereditary history then you’ll be able to know which diseases can potentially be passed down to you, which can include diabetes, high blood pressure, asthma, heart disease or Alzheimer’s. Understanding your genes can also help you understand why you may or may not look like your parents or even other family members.

The human body is so interesting and is still such a mystery. The science field is always discovering something new and amazing things about us as humans, especially that we’re so alike. Genetics make up who were and Sam Kean perfectly describes our genetic makeup in saying, “Genes are like the story, and the DNA is the language that the story is written in.”


If you liked this, why not read about what intelligence is here.

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