The genetics most of us were taught in high school

So what did Mendel figure out? In a monastery garden in the mid-19th century, he pure-bred pea plants and found that traits like seed shape and color passed to offspring in clean, predictable ratios: round or wrinkled, yellow or green, with no variability in between. That result became the foundation of how genetics is taught today because the biologists who championed Mendel's work (e.g., Bateson and Punnett) and integrated it into evolutionary biology in the early 20th century (e.g., Fisher) understood its importance. That's why students still learn about dominant and recessive alleles, homozygotes and heterozygotes, the Punnett square, family pedigrees, and the Hardy-Weinberg Equilibrium of allele frequencies in non-evolving populations. Mendel's discoveries are the foundation of basic genetics education for several good reasons.

What students rarely learn—but biologists know—is how much of that tidiness was built upon the cleverness of Mendel's research design. When he screened pea varieties, he set aside continuously varying traits and focused his analyses on seven traits that he hand-picked because they were largely discrete. And although he did not know it at the time, these traits were governed by genes of large effect. He also worked with pure-breeding lines in a controlled garden, further narrowing the variation he faced. The ratios Mendel observed were real, but the patterns don't always look as discrete when peas grow in the noisier world beyond his garden—in nature. The control, discernment, and mathematics Mendel used to discover his ratios exemplified his careful approach to science. But we rarely teach kids about how Mendel's methods contributed to his findings.

When the biology curriculum does move past Mendel, it never really leaves his garden. The first apparent step beyond is the central dogma: DNA makes RNA makes protein. That may seem like a real move into the molecular complexity of genetics. Yet the “gene encodes a protein” approach that is used in high schools to introduce molecular genetics is often just the engine under the hood of the “gene-for-a-trait” model that Mendelian education expounds. The molecular genetics beyond Mendel is rarely taught in high schools in a way that highlights the environmental contingencies of gene expression or the developmental plasticity of trait expression, or how the independent effects of many different genes can add up to create a continuous trait.

After students integrate the Mendelian model (e.g., dominance, segregation, and independent assortment) with the molecular model (i.e., the central dogma) they apply it to humans by exploring rare single-gene disorders like sickle cell anemia and cystic fibrosis. Each of these monogenic diseases is usually described as a condition that affects a particular group. For example, research by Ann Morning and John Willinsky suggests that 90% or more of textbooks discuss the racial prevalence of human genetic diseases. This means that the basic principles of human genetics that most people learn are often indirectly organized by race.

However, many of the traits stereotypically associated with races are not discretely varying like Mendel's peas. They are complex (quantitative) traits like athleticism or intelligence that vary continuously. And even though sickle shaped blood cells are caused by variation in a single gene, the severity of sickle cell disease is continuous and multifactorial because it is shaped by modifier genes and by social and environmental conditions. Many of the facial traits that humans use to categorize other humans—like eye color—are not determined by variation in one gene either. Nor are they dichotomous. But when the basics of genetics are taught many kids still learn that eye color is dichotomous (brown vs. blue) and determined by a single gene. This story is told every year in high school classrooms composed of students with varying shades of brown, blue, grey and hazel eyes. Occasionally, though rarely, it's even told to brown eyed students with blue eyed parents.

In many ways, the humans that students encounter during the basics of genetics are not the humans of their own classroom. They are more like humans reared in a garden by Mendel. And kids rarely learn why a rearing environment in a breeding experiment fails to model the complexity of human inheritance.

When some of those students go on to take introductory genetics in college, they encounter a similar story as well. Research suggests that 75% of knowledge assessment questions used in introductory genetics courses evaluate knowledge about single-gene inheritance. Only 20% of assessment questions tackle polygenic inheritance and 5% multifactorial inheritance. And since faculty tend to assess only what they teach, introductory genetics in college appears to be mostly focused on the basics. Students have to choose to pursue more advanced genetics courses if they are to learn more about complex trait inheritance.

Of those who study advanced genetics in college, relatively few end up as secondary school biology teachers. Large pluralities of secondary school biology teachers either lack a biology degree (27% of high school and 60% of middle school teachers) or any coursework in genetics beyond the introductory level (44% high school and 67% of middle school teachers). This means that many in the biology teaching workforce are not prepared to move very far beyond Mendel or the basics of molecular genetics. Consequently, American genetics education is a system built to ensure that the public understands Mendelian and molecular genetics, but not the multifactorial models that govern most human complex traits or patterns of genetic variation in human populations. That kind of system can have consequences that reach far beyond the classroom.

Because basic genetics rarely moves beyond the Mendelian foundation, it can leave Americans with an incomplete and often distorted view of human genetics. Students can come away believing that people sort into discrete bins, that most human traits trace back to single genes, and that the differences between groups run deep. It is the Mendelian garden model mistaken for the whole of heredity. When students use that model to make predictions about human beings, race is already included in the equation. That is where the trouble starts, as it has before.

The Problem →

How can a genetics education that never moves beyond Mendel reinforce essentialist beliefs?

When genetics instruction stops at Mendel — single genes, simple inheritance, one gene one trait — it leaves students with an incomplete picture of how genetics works. That incomplete picture has consequences. It predisposes students to believe that racial groups are genetically discrete and internally uniform: that the differences between groups are large and that the variation within groups is small. These beliefs are called genetic essentialism — a misconception illustrated in the left panel of the diagram below, where groups appear genetically separate and non-overlapping. The right panel shows a more scientifically accurate picture: ancestry groups share the majority of alleles that exist in the human genome, with only a small fraction of those genetic differences occurring between groups. Genetic variation is greatest in African populations and slightly lower in populations living further from Africa because of serial founder effects.

Of the 4-5 million nucleotides in the human genome that differ from human to human, studies show that only about 5% differ between humans because of their ancestry. But most people are never taught that. Nor do they learn that roughly 95% of the differences in the variable portion of the human genome (the 0.1% of DNA that differs in humans) occur among individuals of the same ancestry. Because essentialism predicts the opposite pattern—i.e., proportionally more variation between groups than within them—these findings show that essentialism is inaccurate. And when such findings are combined with the fact that complex traits are multifactorial, the weight of evidence reveals why racial stereotypes are genetically wrong: Trait variability is not reducible to genes alone and same race individuals are not genetically uniform.

Put simply, essentialism is flawed because it gets two things wrong about genetics: variability and causation. Why biology education doesn’t teach students that it is wrong is a mystery. Since the time of Fisher in the early 20th century, population geneticists have known that quantitative traits are influenced by many genetic and environmental factors that interact. And since the early 1970s geneticists have replicated the “more variation within than between finding” over and over again using different samples and traits. The one trait where there is more variation between groups than within them is human skin color, but even that trait varies continuously across populations in a way that makes the demarcation of “races” based on discontinuities in skin color that occur with distance from the equator arbitrary. The science that refutes essentialism is largely settled. It constitutes the basic concepts and findings from the last century of human population genetics research. And, it was figured out after the insights of Mendel were woven into evolutionary theory. But unlike Mendel and his peas, it is rarely taught to high school students.

Another thing most people are never taught is why it is inaccurate to conflate race, ethnicity, and ancestry. Ethnicity is a set of sociopolitical categories shaped by history and culture, not DNA, while ancestry describes the actual paths by which DNA is inherited across populations. Throughout history, race has never had a consistent definition, but many people believe it refers to groups of people who differ in their physical and/or behavioral traits because of their biology, and often in ways that comport with essentialism. A lot of people conflate ethnicity, race, and ancestry in part because the biology curriculum rarely defines and discusses the differences between these concepts. This page uses racial terms when referring to how students reason about human groups and it uses ancestry terms when discussing genetics. Treating ethnic differences as if they are always caused by genetic ancestry is an example of an essentialist misunderstanding.

Such misunderstandings are not uncommon. Research shows that US high school students and adults have inaccurate views about human population genetics. For example, they tend to think that 37% of human genetic differences are racial in origin. That number is not accurate. It is similar to the amount of genetic differences across dog breeds, but it’s seven times greater than the amount of genetic differences across human ancestry groups. The reason such misconceptions persist in our society is not only because they are rarely addressed by genetics education. It’s also because Mendelian genetics education can cause students to develop distorted views about human populations.

Several studies suggest that a genetics education that never moves beyond the foundation of Mendel increases the risk that students develop essentialist views about race. Those same studies also show that when education moves beyond the Mendelian foundation, and into the complexity of genomics, then students develop a more accurate view of human difference. That’s good news, because studies show that students who are less likely to endorse essentialism exhibit higher academic achievement in college biology courses. Genetic essentialism is not just scientifically wrong either — it is socially dangerous. Research shows it fuels intergroup hostility, support for eugenic policies, discrimination, and disinterest in cross-racial friendships.

The rest of this science page unpacks why genetics education needs to move beyond Mendel and what the benefits of that kind of education are. The work described here was led by Brian Donovan — founder of Beyond Mendel LLC — and it has earned Brian several awards, including the Genetics Society of America’s Elizabeth W. Jones Award for Excellence in Education in 2026 and the NARST Early Career Research Award. The American Genetic Association Humane Genomics Education Award was named in honor of this work.

The previous pages show how instruction that never moves beyond Mendel may promote the development of genetic essentialism. The studies on this page show how instruction beyond Mendel can prevent the development of essentialism and reverse it. Instruction that challenges essentialism by helping students understand inheritance beyond Mendel is known as humane genomics instruction. Such instruction refutes essentialism by teaching what Mendel’s framework left out: human population genetics and the multifactorial basis of complex traits. Humane genomics instruction helps students understand why it is incorrect to believe that each race possesses special genes that makes them inherently good at some things, but bad at other things.

Donovan et al. (2019) · Science Education

Can moving beyond Mendel into the complexity of humane genomics reduce essentialist beliefs about race?

If Mendelian instruction increases essentialism by reinforcing the perception that groups are genetically separate and internally uniform, then teaching students about actual patterns of genetic variation in humans should reduce essentialism. Proportionally, most of the variation in the human genome exists among individuals of the same ancestry group. Individuals of different groups have genomes that are only about 5% more different than the genomes of two randomly picked people of the same ancestry group. Students rarely learn these ideas about patterns in the human genome because they are not a part of the Mendelian foundation that defines genetics education.

Across three randomized controlled trials, Brian and his team have demonstrated that learning about this aspect of the human genome can cause significant reductions in students’ genetic essentialist beliefs about race. When students learn about this finding, they develop a more accurate perception of between-group difference, and this causes them to disbelieve essentialist distortions of inheritance. Students become less likely to believe that each race has its own special genes that determine their abilities and potential. Play with the data from this study and then read the paper to learn more about the details of these studies.

Donovan et al. (2020) · Journal of Research in Science Teaching

How does a strong foundation in genomics beyond Mendel interact with humane genomics education to affect essentialism?

The 2019 studies showed that humane genomics instruction works to reduce belief in genetic essentialism. But they raised a follow-up question: does this change depend on what students already know about genomics? Genomics is the scientific term for what lies beyond Mendel. It involves models like polygenic inheritance and multifactorial inheritance. Students who already understand these more complex genomic models may be better equipped to grasp why genetic determinism is an implausible explanation for the complex traits that people racially stereotype. In a randomized controlled trial with 721 high schoolers, Brian and his team confirmed this hypothesis in two ways. First, they showed for the first time that high school students with greater genomics knowledge tend to exhibit lower belief in genetic essentialism and less belief in the discreteness of racial groups. If you play with the data below, you can see these effects when the switch is turned off.

The second thing Brian and his team found was that students with greater prior genomics knowledge showed significantly greater reductions in perceived racial differences and genetic essentialism in response to humane genomics instruction. You can see this effect when you turn on the prior genomics knowledge button. Students with below average genomics knowledge did not show statistically meaningful changes in response to instruction. Whereas students with a lot of prior genomics knowledge showed large and meaningful changes. So the curriculum worked more powerfully for students who arrived with more of a foundation in the genomics beyond Mendel. Play with the data and read the paper to learn more about the details of these studies.

Donovan et al. (2024) · Science

What does humane genomics instruction do at scale?

The results of the previous study showed that students with more knowledge of multifactorial inheritance changed more in response to humane genomics instruction about patterns of genetic variation in human populations. On the basis of these findings, Donovan’s team revised the humane genomics curriculum by adding in additional instruction about how complex traits are influenced by multiple genetic and environmental factors operating within and between groups. The new curriculum helped kids understand that the environment can still be a better explanation for trait variation between groups even when trait variation within a group is heritable. John Landis’s movie Trading Places (1983) captures the new story that students learned with this revision.

In that movie, two wealthy old men bet on whether Eddie Murphy or Dan Aykroyd will succeed when they trade places to experience each other’s life circumstances. It’s basically a comedic description of a common garden experiment designed to refute genetic determinism. Hold the genes constant, vary the social environment radically, and see what happens. The film’s punchline is that environment swamps genetic determination. That is the same logic that humane genomics instruction teaches formally about populations — and it is the logic that population geneticists use to refute the belief that group differences in intelligence and ability are written in the genes.

To test whether the new humane genomics curriculum would work, Donovan’s research team conducted a much larger study. The early studies on humane genomics instruction were conducted in small, relatively homogeneous settings that made it easier to detect a treatment effect. They preregistered and then conducted a crossover trial using schools in multiple states. This means they randomly assigned half of the classrooms in their study to receive Mendelian instruction first, and then Humane Genomics instruction afterward. The other half of classes got the same curricula in the opposite order. Every classroom went beyond Mendel in a different order. Brian only conducted and reported the statistical tests he registered as hypotheses before the study began.

The results: humane genomics instruction produced significantly greater gains in genomics knowledge, greater reductions in genetic essentialism, and greater increases in the belief that racism — not biology — creates social disparities. This means the kids had learned the main idea from the movie Trading Places.

But that’s not all they learned. Humane genomics instruction also reduced the emotional cost of learning genetics for students of color. Because the study used a crossover design — every student received both conditions — it was able to show that students of color reported significantly less anxiety, confusion, and frustration when learning from the humane genomics materials as compared to the Mendelian materials. Self-identified white students had statistically similar emotional responses to each form of instruction.

In those ways, the curriculum resonates with Theodore Melfi’s movie Hidden Figures (2016). That film captures what it’s like to be a Black female scientist working at NASA when many of your colleagues have essentialist ideas about race and gender. It shows not just the intellectual burden of working against an assumption that your group’s underrepresentation in science is biological, but the emotional weight of being in a room where people hold such assumptions. Humane genomics instruction appears to change what that room feels like. Brian’s team estimates that when humane genomics instruction is implemented in a classroom of 30 students it causes two students to fully change their essentialist beliefs. That means two students per classroom move from believing to disbelieving the idea that races differ in intelligence because of genetics. That might not sound like much until you consider what it might feel like to go to school with someone who holds those stereotypes about you. And the data showed that emotional effect, too.

The studies show humane genomics instruction reduces belief in genetic essentialism. Move onto the curriculum page to learn how.

The Curriculum →

Wedow, Jeong, Thompson, … Donovan (2026) · Human Genetics and Genomics Advances

How does humane genomics education create a cognitive change in the minds of students?

Humane genomics instruction works at scale and shifts a variety of racial beliefs. This study asked a deeper question: how does it work, and for whom does it work best? It explored if the effectiveness of humane genomics instruction varies by self-identified race, gender, or political orientation, and if and how the cognitive mechanisms that lead to a reduction in essentialism vary because of a student’s prior knowledge about the genomics beyond Mendel. The experiments were carried out with 2000 biology and psychology undergraduates at a large university in two different preregistered randomized trials.

These studies found that humane genomics instruction was equally effective for all subgroups of students and reduced their essentialist beliefs through four cognitive mechanisms. Humane genomics instruction caused reductions in genetic essentialist beliefs about race by helping students to (1) perceive more variability among individuals of the same race; (2) perceive less variability between or across races; (3) attribute complex traits like intelligence and science ability less to genes and (4) more to the environment. All four mechanisms matter. But the mechanisms of change that made the most difference in terms of reducing essentialism were the pathways described in points two and three. And the students who began the humane genomics learning experience with more knowledge of multifactorial inheritance changed more through pathway three. This means that a foundation in the genomics beyond Mendel is most important for helping students see through the distortion of essentialism. Self-identified race, gender, and political worldview do not drive the change. Knowledge of the genomics beyond Mendel does.

What does the instruction actually look like — and why does it produce these effects?

The five studies above document that humane genomics instruction works, for whom it works best, and through which cognitive pathways. The curriculum targets three specific misconceptions that are inappropriate for understanding complex traits and questions of race — beliefs in uniformity, discreteness, and genetic determination — and replaces them with more accurate models through a carefully designed sequence of instructional experiences. The primary way the curriculum helps kids to change these beliefs is through an evidence-laden narrative (ELN) involving two characters who have divergent views about race. Each character has an inaccurate model of race, and through the story of the curriculum the characters model how to argue about evidence, change their thinking, and develop models aligned with the evidence.

If you want to see how the pedagogy helps kids change their mental models of inheritance click on the box below. It shows how the curriculum uses contrasting models of human difference to help students see the visual flaws of inaccurate models of inheritance. The paper below that toggle unpacks how the instruction moves students from the misconception models to the accurate models through a variety of research-based instructional supports. Read that paper if you are serious about moving beyond Mendel and into the complexity of humane genomics instruction. The paper will help you understand how the curriculum works and how to adapt the curriculum for your classroom. It also unpacks how the curriculum distinguishes race, ethnicity, and ancestry using the framework in the National Academies’ 2023 report on population descriptors in genetics.

Access the research-based curriculum

The science is done. The curriculum is written. What comes next depends on who decides it matters. The HGL curriculum (CC-BY-NC-ND) is freely available to any teacher who wants to use it — preserved permanently with citable DOIs for each lesson. Brian and his collaborators have made it free so that any teacher can move beyond Mendel and help their students develop more accurate and humane views of human genetic variation.

To learn more about who Brian is, why he did this work, and where he is going next see the about page.

About Brian →