The "gay gene" and other things people often get wrong about genetics
Don’t be fooled! We uncover some of the most common misconceptions about genetics.
Genetics underpins many of the modern advances in biological science, from treating cancers to developing sustainable agriculture, and even attempting to — in a way — bring back the dinosaurs. Recent breakthroughs in gene editing are also promising to help cure diseases once thought incurable. There’s no doubt genetics is incredibly important to today’s world.
But how much do you know about genes and DNA? If you get all your info from non-scientists, perhaps it’s not a lot. A quick look at the media often sends geneticists into fits of frustration with the falsehoods and factual inaccuracies being perpetuated by some newspapers, TV shows, and movies.
So don’t be fooled! Here are some of the most common misconceptions about genetics, and what the deal really is with DNA.
There is no single gene for XHow many times have you seen a variation of the headline “Scientists find the gene for X”? Is there a gay gene? How about a left-wing gene, or an obesity gene? If you read the news, you’d get the impression that there are. But in reality, it’s not so simple.
"Most traits that we care about are influenced by many genes,” says Professor Phil Batterham, a geneticist at the University of Melbourne. “While variation in a single gene may sometimes have a significant influence on a trait, when you read the words ‘the gene for,’ you are likely reading nonsense.”
Our genes interact with our environment (what we eat, how we were raised, where we live, etc.) to produce the unique person we each are. There is no single gene for being exceptionally tall, for example — multiple genes influence height, but so does childhood nutrition. Even traits that aren’t particularly influenced by the environment, such as hair or eye colour, are usually controlled by multiple genes.
“The media wants a digestible story, so I can understand why this misconception is perpetuated that there is a single gene coding for these traits, when in fact it's a much more complex story,” says Dr Camilla Whittington, an evolutionary geneticist at the University of Sydney. “But that's hard to get across in popular media."
It’s not us having “different genes” that causes diseaseBy and large, as humans, we all have the same collection of genes. What differs between individuals are the particular gene variants we each have, called ‘alleles’ by geneticists. Alleles vary in their precise DNA lettering, and it’s these lettering changes that influence our bodies and our health.
“Often genes get a bad rap in the media where they are so often associated with diseases,” says Prof Batterham. “In reality, we all have the same set of genes that are required for our bodies to develop and function normally.”
Most diseases, such as heart disease or cancer, are influenced by many alleles, not just one. Having these “unhealthy” alleles also doesn’t doom you to illness — they typically only increase your likelihood of developing the disease at some point in your life. Exceptions like cystic fibrosis and Huntington’s disease, which have solitary and unavoidable genetic causes, are in the minority.
So when you see a gene being blamed for causing bad health, remember that it’s probably a delinquent allele causing the problem, not the gene as a whole. In other words, don’t be unfair to your genes.
Genetic modification is not inherently dangerousDo you get squeamish thinking about eating a plant that contains fish DNA? Popular culture is rife with depictions of genetically modified (GM) food as gross and dangerous “Frankenfood”.
But there are many advantages to GM food, such as putting a cold-resistance gene from the winter flounder into tomatoes to help improve crop yields, or putting extremely safe insecticide-making genes into cotton.
"We've been genetically modifying things since we first started domesticating wolves and breeding crops,” says Dr Whittington. "The problem people have with it is putting in DNA from very distantly related organisms."
But there’s no reason to think a piece of DNA from one organism being put into another is inherently dangerous. After all, in the case of the “fish-tomatoes,” we were already eating that piece of DNA every time we ate fish — and all DNA looks the same to our highly acidic stomach, which breaks it down into its building blocks regardless of origin.
How can people get just the facts about genetics?What’s the best way to clear up these misconceptions? Not everyone is reading articles on the topic in SBS Science — although we wish they would.
“It's about the media and the general public becoming more scientifically literate,” says Dr Whittington. “Part of that is up to us geneticists — we have to communicate our science better so that we're sending the right message to the public.”
Hear that, geneticists? You need to speak up. But perhaps we should also pay more attention to what they’re saying.
After all, we don’t inherit knowledge about genetics from our genes — we need to get it from the environment.