In biology classrooms across the world, students learn to roll their tongues. It’s almost a rite of passage, often folded into a lesson about Mendelian genetics. It’s supposed to be a simple demonstration: if you can curl your tongue into a tube, you probably have the “tongue-rolling gene.” If you can’t, you don’t. Blame your parents.

But what if that lesson is wrong? What if many other genetic myths are simply wrong as well (or at least misleading)? Simon Fisher, a geneticist at the Max Planck Institute, Nijmegen, recently pointed out just how persistent (and pervasive) some of these myths are. Let’s go through some of them.

Tongue rolling? Not genetic

This is the “gateway myth”. Many biology teachers (and even some textbooks) from the mid-20th century onward have taught that tongue rolling is a dominant genetic trait. If your parents can roll it, so can you.

But modern studies have failed to find a single gene responsible for the trick. A 1952 study already challenged the idea, showing that identical twins didn’t always share the trait. Studies from the 1980s put even more doubt on this idea. Environment, learning, and even mimicry may all play a role.

So why is this myth still in circulation? It sticks in your mind, and it’s easy to present to kids. But that stickiness has come at the cost of scientific rigor.

Attached earlobes

This one seems simple: attached earlobes are recessive; free-hanging lobes are dominant. But once again, reality doesn’t seem to cooperate.

While kids in some biology classes are told tales of an “earlobe gene” that directs whether the earlobe is attached or not, studies comparing family trees have found no consistent inheritance pattern. The trait appears more continuous than binary, suggesting multiple genes—and possibly developmental randomness—are at play.

“A closer look reveals that earlobe attachment doesn’t fall neatly into two types, but encompasses much variation,” writes Fisher.

Eye color

Surely at least eye color must be simple. Blue is recessive, brown is dominant. Right? If both parents are blue-eyed, a child’s eyes must be blue.

Well… not quite.

Eye color is influenced by several genes, and even the blue vs. brown divide is too simplistic. Some people have hazel eyes, or one brown and one green, or subtle shifts that aren’t easily categorized.

One key gene, OCA2, does play a major role, but it’s just part of the bigger picture. And the picture is one of a multigene orchestra, not a solo act.

Widow’s Peak

The V-shaped hairline, often linked with villains in cartoons, is also part of genetic lore. The widow’s peak tends to be a “bad guy” feature. Dracula and the Joker, for example, both have a widow’s peak.

Many biology courses teach it as a dominant trait.

Yet no peer-reviewed study has ever conclusively identified a gene for widow’s peak. Hairline shape, like many traits, likely results from a mix of genes, hormonal effects, and chance.

There hasn’t been enough research on this one to conclusively say what causes it, but it seems very likely that several genes are at play.

Hand-Clasping Preference

Fold your hands. Which thumb is on top? This simple gesture has been used to illustrate genetic inheritance, and again, it’s something you can easily demonstrate in class

Yup, this also isn’t strictly genetic.

Studies from the late 1990s and early 2000s found that hand clasping doesn’t follow clear genetic patterns. While a strong genetic component is evident, it’s not a simple rule. It may involve some heritable component, but culture and randomness likely play bigger roles.

The “Language Gene”

FOXP2 was once hailed as “the gene for language.” It emerged from studies of a British family with severe speech difficulties. When scientists found a mutation in FOXP2, they thought they were on to something.

They were. But language is not located in a single gene.

Instead, language depends on dozens of genes, brain networks, and years of interaction with other humans. “The gene for X” idea doesn’t hold in general, whether it’s the gene for intelligence, music, or homosexuality.

Why This Matters

There’s no shame in teaching simplified models. But we need to mark them clearly as models, not truths.

Instead of asking whether a trait is genetic, we should ask how it’s genetic. What genes are involved? How strong is the effect? What else plays a role?

This shift—from black-and-white to shades of gray—isn’t just more accurate. It’s more interesting. It’s closer to how biology actually works.