Look in the mirror. Who do you see? Do you see someone with blue or brown eyes? Is that person short or tall, a man or a woman? Do you see a face with freckles, or someone who’s bald?
- Alexandra
- Feb 16, 2024
- 5 min read
Easy questions. easy answers. After all, that person in the mirror is you. You know you better than any one else. Or do you?
We humans like to think of ourselves as unique beings, and in many respects, we are. Yet, while we do have differences among us, we’re all pretty much the same. How can that be? Take a minute to find the old family photo album. Look at the pictures of your parents and their parents—your grandparents. Why do you look a bit, but not exactly, like your mom and dad? Why does your sister seem to have the same nose as your grandmother, but yours is much thinner?
Why? All these questions seem funny, a bit odd perhaps, yet all have serious answers. Each has to do with genetics, the science of heredity. Genetics helps us understand the biological programming of all living organisms, including humans, dogs, trees, grapevines, or flu viruses. Heredity is the expression of traits, such as hair and eye color—and, yes, the ability to wiggle ears—and how they are passed from one generation to another.
Genetics impacts our lives on a daily basis. Just glance at a newspaper or an internet news feed. One day not that long ago, one news story told us how an ancient plague helped determine the genetic makeup of modern Europeans, while another marveled at how genetics could lead to new therapies to treat epilepsy.
Still another headline pointed out that our consumption of coffee depends on our genes. But there’s more. Lots more. Because scientists can sequence (determine the order of DNA bases) and read our genetic blueprints, doctors are now able to detect some diseases just by taking samples of our blood. Genetics is giving us new ways to attack specific ailments by focusing on the genes that make up the disease, too.
Did you know?
The great majority of cancers, some 90-95% of cases, are due to environmental factors. The remaining 5-10% are due to inherited genetics.
Today, about 8% of the human DNA is made of leftovers from the viruses our ancestors fought off. Scientists used to think these strange bits had no purpose. But when they removed them from cells in a lab, other nearby genes were no longer able to trigger the immune system to fight off new virus attacks. As it turns out, those ancient viruses have been protecting us against new ones.
If you have a bone marrow transplant, your blood can have the donor’s DNA and your salival and hair DNA will be your own.
Human DNA is 50% similar to bananas.
At least six genes are responsible for how our bodies process caffeine.
Men have lost the DNA code that once made human penises spiny.
When identical twins procreate with another set of identical twins, their offspring are both genetic siblings and social cousins.
You may be wondering, “what gene controls hair color?” or “what eye color will my baby have?” Most genetic traits result from a combination of both parents’ genetic codes. But when it comes to tracing certain traits to certain parents, we direct our focus to the genes contained in the sex chromosomes.
Through cell division and fertilization, humans acquire 46 chromosomes containing their unique DNA; 23 from mom, and 23 from dad. Sex-linked genes are expressed according to the genetic material on sex chromosomes, the 23rd pair, which differ between sexes. Where females have two X chromosomes, males have one X chromosome and one Y chromosome, with certain genetic traits found exclusively on either one.
Genes are the blueprint for your body, containing all of the instructions for producing proteins that determine how your body functions. We inherit one set of genes from our father and one set from our mother, with roughly equal contributions from each. All of us get three feet of DNA from our father and three feet from our mother.
Although most inherited genes are passed on from both parents, some traits are directly linked to the mother, from certain genetic diseases to hair and eye color.
How much do you inherit from your mother?
Women inherit 50% of their DNA from each parent.
Men inherit approximately 51% from their mother and only 49% from their father.
According to studies, mitochondrial DNA is inherited solely from the mother. Mitochondrial diseases are chronic hereditary disorders that occur when mitochondria DNA has defects or mutations. Mitochondrial diseases can appear at any age, but usually appear at birth and can affect nearly every organ of the body, including the brain, nerves, muscle, kidney,hear, liver, eyes, ears, and pancreas. About 1 in every 5,000 people is affected by hereditary mitochondrial disorder. Because of the variety of symptoms and organ systems involved, mitochondrial illnesses are frequently misdiagnosed. Many disorders can cause secondary mitochondrial dysfunction and have an effect on other diseases. Examples include: Alzheimer’s disease, Muscular dystrophy, Lou Gehrig’s disease, Diabetes, Cancer.
Physical features such as hair color, hair texture, hairline, skin, and varicose veins are inherited from your mother.
Researchers from Glasgow's Medical Research Council Social and Public Health Sciences Unit discovered that socioeconomic position and education have an effect on IQ. According to their findings, the best predictor of intelligence was the mother's IQ.
According to a study published in the journal Sleep Medicine, mothers pass on their sleeping habits to their children. Children of mothers with insomnia tend to fall asleep later and get less sleep.
According to a few studies, if the mother has lower levels of serotonin, herchild is more likely to develop ADHD later in life. Genes that regulate serotonin production in the brain are passed down from mother to child and appear to have an impact on the ability to focus.
What do we get from dad?
Dads are responsible for the biological sex of their baby. It’s one of the physical traits that’s 100% determined by paternal genes and/or dads.
If a man becomes a father later in life, there is less quality sperm. This is one of the reasons why older fathers can pass on mutant genes to their children which can lead to mental illnesses or mental health issues. This means children can develop conditions such as hyperactivity or bipolar disorder. However, recent research has noted that genetic influence on mental disorders may be less strong than previously thought. Mental disorders have a genetic link, but it is only 10-20% with a variety of other factors influencing mental health.
There are a number of factors that go into the size and shape of our body, and genetics certainly has a lot to do with it. Dad’s adipose tissue, however, seems to have a bigger role in passing on excess fat compared to mom’s. Some body fat is necessary for general health and survival. But, too much can lead to a number of health issues and complications. In the body, there are two types of fat cells that can be considered “good” or “bad.” Brown fat is responsible for burning calories and maintaining a safe body temperature. White fat, on the other hand, stores excess energy (calories) as fat. Researches have identified that brown fat is maternally inherited, while white fat is paternally inherited. This means that dad’s genes are more likely to contribute to the development of excess fat. Thanks, Dad☹.
Trying to understand genetics and its impact on our lives and society might seem like a job best left to academics, but it’s not. Genetics affects all of us, sometimes positively, other times not so much. Just imagine, for example, a day when you won’t have to worry about cancer because a scientist has engineered your DNA to make you immune to such a disease. If it feels as if we’re living in a brave new world, we are. That’s because it’s in our genes.
What is genetic mutation? Why do genes mutate? CAN WE CHANGE OUR GENES? To be continued...
Alexandra Alexander
