Carl Zimmer writes at Skeptical Inquirer Seven Big Misconceptions About Heredity. Excerpts in italics with my bolds

It’s been seven decades since scientists demonstrated that DNA is the molecule of heredity. Since then, a steady stream of books, news programs, and episodes of CSI have made us comfortable with the notion that each of our cells contains three billion base pairs of DNA, which we inherited from our parents. But we’ve gotten comfortable without actually knowing much at all about our own genomes.

If you want to get your entire genome sequenced—all three billion base pairs in your DNA—a company called Dante Labs will do it for $699. You don’t need whole genome sequencing to learn a lot about your genes, however. The 20,000 genes that encode our proteins make up less than 2 percent of the human genome. That fraction of the genome—the “exome”—can be yours for just a few hundred dollars. The cheapest insights come from “genotyping”—in which scientists survey around a million spots in the genome known to vary a lot among people. Genotyping—offered by companies such as 23andMe and Ancestry—is typically available for under a hundred dollars.

Thanks to these falling prices, the number of people who are getting a glimpse at their own genes is skyrocketing. By 2019, over twenty-five million worldwide had gotten genotyped or had their DNA sequenced. At its current pace, the total may reach 100 million by 2020.

There’s a lot we can learn about ourselves in these test results. But there’s also a huge opportunity to draw the wrong lessons.

Many people have misconceptions about heredity—how we are connected to our ancestors and how our inheritance from them shapes us. Rather than dispelling those misconceptions, our growing fascination with our DNA may only intensify them. A number of scientists have warned of a new threat they call “genetic astrology.” It’s vitally important to fight these misconceptions about heredity, just as we must fight misconceptions about other fields of science, such as global warming, vaccines, and evolution. Here are just a few examples.

Misconception #1: Finding a Special Ancestor Makes You Special

You can join the Order of the Crown of Charlemagne if you can prove that the Holy Roman Emperor is your ancestor. It’s a thrill to discover we have a genealogical link to someone famous—perhaps because that link seems to make us special, too.

But that’s an illusion. I could join the Mayflower Society, for example, because I’m descended from a servant aboard the ship named John Howland. Howland’s one claim to fame is that he fell out of the Mayflower. Fortunately for me, he got fished out of the water and reached Massachusetts. But I’m not the only fortunate one; by one estimate, there are two million people who descend from him alone.

Mathematicians have analyzed the structure of family trees, and they’ve found that the further back in time you go, the more descendants people had. (This is only true of people who have any living descendants at all, it should be noted.) This finding has an astonishing implication. Since we know Charlemagne has living descendants (thank you, Order of the Crown!), he is likely the ancestor of every living person of European descent.

Misconception #2: You Are Connected to All Your Ancestors by DNA

But genetics do not equal genealogy. It turns out that practically none of the Europeans who descend from Charlemagne inherited any of his DNA. All humans, in fact, have no genetic link to most of their direct ancestors.

The reason for this disconnect is the way that DNA gets passed down from one generation to the next. Every egg or sperm randomly ends up with one copy of each chromosome, coming either from a person’s mother or father. As a result, we inherit about a quarter of our DNA from each grandparent—but only on average.

If you go back a few generations more, that contribution can drop all the way to zero. . . While it is true that you inherit your DNA from your ancestors, that DNA is only a tiny sampling of the genes in your family tree.

Even without a genetic link, though, your ancestors remain your ancestors. They did indeed help shape who you are—not by giving you a gene for some particular trait, but by raising their own children, who then raised their own children in turn, passing down a cultural inheritance along with a genetic one.

Misconception #3: Ancestry Tests Are as Reliable as Medical Tests

Millions of people are getting ancestry reports based on their DNA. My own report informs me that I’m 43 percent Ashkenazi Jewish, 25 percent Northwestern European, 23 percent South/Central European, 6 percent Southwestern European, and 2.2 percent North Slavic. Those percentages sound impressive, even definitive. It’s easy to conclude that ancestry reports are as reliable as stepping on a scale at the doctor’s office to get your height and weight measured.

That is a mistake, and one that can cause a lot of heartbreak. To estimate ancestry, researchers compare each customer to a database of thousands of people from around the world. . . They can identify stretches of DNA that are likely to have originated in a particular part of the world. While some matches are clear-cut, others are less so. As a result, ancestry estimates always have margins of error—which often go missing in the reports customers get.

These estimates are going to get better with time, but there’s a fundamental limit to what they can tell us about our ancestry. . . Researchers are getting glimpses of those older peoples by retrieving DNA from ancient skeletons. And they’re finding that our genetic history is far more tumultuous than previously thought. Time and again, researchers find that the people who have lived in a given place in recent centuries have little genetic connection to the people who lived there thousands of years ago. All over the world, populations have expanded and migrated, coming into contact with other populations. . . If you want to find purity in your ancestry, you’re on a fool’s errand.

Misconception #4: There’s a Gene for Every Trait You Inherit

Mendel is a great place to start learning about heredity but a bad place to stop. There are some traits that are determined by a single gene. Whether Mendel’s peas were smooth or wrinkled was determined by a gene called SBEI. Whether people develop sickle cell anemia or not comes down to a single gene called HBB. But many traits do not follow this so-called Mendelian pattern—even ones that we may have been told in school are Mendelian.

Consider your ear lobes. For decades, teachers taught that they could either hang free or be attached to the side of our heads. The sort of ear lobes you had was a Mendelian trait, determined by a single gene. In fact, our ear lobes typically fall somewhere between the two extremes of strongly attached to fully free. In 2017, a team of researchers compared the ear lobes of over 74,000 people to their DNA. They looked for genetic variants that were common in people at either end of the ear-lobe spectrum. They pinpointed forty-nine genes that appear to play a role in determining how attached they are to our heads. There well may be more waiting to be discovered.

The genetics of ear lobes is actually very simple compared to other traits. Studying height, for example, scientists have identified thousands of genetic variants that appear to play a role. The same holds true for our risk of developing diabetes, heart disease, and other common disorders. We can’t expect to find a single gene in our DNA tests that determines whether we’ll die of a heart attack. Nor should we expect easy fixes for such complex diseases by repairing single genes.

Misconception #5: The Genes You Inherit Explain Exactly Who You Are

Take, for example, a recent study on how long people stay in school. Researchers examined DNA from 1.1 million people and found over 1,200 genetic variants that were unusually common either in people who left school early or in people who went on to college or graduate school. They then used the genetic differences in their subjects to come up with a predictive score, which they then tried out on another group of subjects. They found that in the highest-scoring 20 percent of these subjects, 57 percent finished college. In the lowest-scoring 20 percent, only 12 percent did.

But these results don’t mean that how long you stayed in school was determined before birth by your genes. Getting your children’s DNA tested won’t tell you if you should save up money for college tuition or not. Plenty of people in the educational attainment study who got high genetic scores dropped out of high school. Plenty of people who got low scores went on to get PhDs. And many more got an average amount of education in between those extremes. For any individual, these genetic scores make predictions that are barely better than guessing at random.

This confusing state of affairs is the result of how genes and the environment interact. Scientists call a trait such as how long people stay in school “moderately heritable.” In other words, a modest amount of the variation in education attainment is due to genetic variation. Lots of other factors also matter, too—the neighborhoods where people live, the quality of their schools, the stability of their family life, their income, and so on. What’s more, a gene that may have an influence on how long people stay in school in one environment may have no influence at all in another.

Misconception #6: You Have One Genome

According to this assumption, you will find an identical sequence of DNA in any cell you examine. But there are many ways in which we can end up with different genomes within our bodies.

Fairchild is known as a chimera. She developed inside her mother alongside a fraternal twin. That twin embryo died in the womb, but not before exchanging cells with Fairchild. Now her body was made up of two populations of cells, each of which multiplied and developed into different tissues. In Fairchild’s case, her blood arose from one population, while her eggs arose from another.

It’s unclear how many people are chimeras. Once they were considered bizarre rarities. Scientists became aware of them only in cases such as Lydia Fairchild’s, when their mixed identity made itself known. In recent years, researchers have been carrying out small-scale surveys that suggest that perhaps a few percent of twins are chimeras, but the true number could be higher. As for chimeric mothers, they may be the rule rather than the exception. In a 2017 study, researchers studied brain tumors taken from women who had sons. Eighty percent of them had Y-chromosome-bearing cells in their tumors.

Chimerism is not the only way we can end up with different genomes. Every time a cell in our body divides, there’s a tiny chance that one of the daughter cells may gain a mutation. At first, these new aberrations—called somatic mutations—seemed important only for cancer. But that view has changed as new genome-sequencing technologies have made it possible for scientists to study somatic mutations in many healthy tissues. It now turns out that every person’s body is a mosaic, made up of populations of cells with many different mutations.
Misconception #7: Genes Don’t Matter Because of Epigenetics

The notion that our genes are our destiny can trigger an equally false backlash: that genes don’t matter at all. And very often, those who push against the importance of genetics invoke a younger, more tantalizing field of research: epigenetics.

Our cells use many layers of control to make proper use of their genes. They can quickly turn some genes on and off in response to quick changes in their environment. But they can also silence genes for life. Women, for example, have two copies of the X chromosome, but in early development, each of their cells produces a swarm of RNA molecules and proteins that clamp down on one copy. The cell then only uses the other X chromosome. And if the cell divides, its daughter cells will silence the same copy again.

One of the most tantalizing possibilities scientists are now exploring is whether certain epigenetic “marks” can be inherited not just by daughter cells but by daughters—and sons. If people experience trauma in their lives and it leaves an epigenetic mark on their genes, for example, can they pass down those marks to future generations?

If you’re a plant, the answer is definitely yes. Plants that endure droughts or attacks by insects can reprogram their seeds, and these epigenetic changes can get carried down several generations. The evidence from animals is, for now, still a mixed bag. . . But skeptics have questioned how epigenetics can transmit these traits through the generations, suggesting that the results are just statistical flukes. That hasn’t stopped a cottage industry of epigenetic self-help from springing up. You can join epigenetic yoga classes to rewrite your epigenetic marks or go to epigenetic psychotherapy sessions to overcome the epigenetic legacy you inherited from your grandparents.

As Jordan Peterson has pointed out, an ideology takes a partial truth and asserts it as the whole truth, and nothing but the truth.  With global warming\climate change, we see how a complex, poorly understood natural system is reduced to a simplistic tweet:  “Ninety-seven percent of scientists agree: climate change is real, man-made and dangerous.”  That is the work of a small but dedicated group of ideologues who captured and overturned climate science so that it now only functions as a tool of political operatives.

The post shows how decades of painstaking work in neurological science are being attacked by gender ideologues, who cannot tolerate any biological differences between men and women.

Larry Cahill writes at Quillette Denying the Neuroscience of Sex Differences Excerpts in italics with my bolds.

For decades neuroscience, like most research areas, overwhelmingly studied only males, assuming that everything fundamental to know about females would be learned by studying males. I know — I did this myself early in my career. Most neuroscientists assumed that differences between males and females, if they exist at all, are not fundamental, that is, not essential for understanding brain structure or function. Instead, we assumed that sex differences result from undulating sex hormones (typically viewed as a sort of pesky feature of the female), and/or from different life experiences (“culture”). In either case, they were dismissable in our search for the fundamental. In truth, it was always a strange assumption, but so it was.

Gradually however, and inexorably, we neuroscientists are seeing just how profoundly wrong — and in fact disproportionately harmful to women — that assumption was, especially in the context of understanding and treating brain disorders. Any reader wishing to confirm what I am writing can easily start by perusing online the January/February 2017 issue of the Journal of Neuroscience Research, the first ever of any neuroscience journal devoted to the topic of sex differences in its entirety. All 70 papers, spanning the neuroscience spectrum, are open access to the public.

In statistical terms, something called effect size measures the size of the influence of one variable on another. Although some believe that sex differences in the brain are small, in fact, the average effect size found in sex differences research is no different from the average effect size found in any other large domain of neuroscience. So here is a fact: It is now abundantly clear to anyone honestly looking, that the variable of biological sex influences all levels of mammalian brain function, down to the cellular/genetic substrate, which of course includes the human mammalian brain.

The mammalian brain is clearly a highly sex-influenced organ. Both its function and dysfunction must therefore be sex influenced to an important degree. How exactly all of these myriad sex influences play out is often hard, or even impossible to pinpoint at present (as it is for almost every issue in neuroscience). But that they must play out in many ways, both large and small, having all manner of implications for women and men that we need to responsibly understand, is now beyond debate — at least among non-ideologues.

Recognizing our obligation to carefully study sex influences in essentially all domains (not just neuroscience), the National Institute of Health on January 25, 2016 adopted a policy (called “Sex as a Biological Variable,” or SABV for short) requiring all of its grantees to seriously incorporate the understanding of females into their research. This was a landmark moment, a conceptual corner turned that cannot be unturned.

But the remarkable and unprecedented growth in research demonstrating biologically-based sex influences on brain function triggered 5-alarm fire bells in those who believe that such biological influences cannot exist.

Since Simone de Beauvoir in the early 1950s famously asserted that “One is not born, but rather becomes, a woman,” and John Money at Johns Hopkins shortly thereafter introduced the term “gender” (borrowed from linguistics) to avoid the biological implications of the word “sex,” a belief that no meaningful differences exist in the brains of women and men has dominated U.S. culture. And God help you if you suggest otherwise! Gloria Steinem once called sex differences research “anti-American crazy thinking.” Senior colleagues warned me as an untenured professor around the year 2000 that studying sex differences would be career suicide. This new book by Rippon marks the latest salvo by a very small but vocal group of anti-sex difference individuals determined to perpetuate this cultural myth.

A book like this is very difficult for someone knowledgeable about the field to review seriously. It is so chock-full of bias that one keeps wondering why one is bothering with it. Suffice to say it is replete with tactics that are now standard operating procedure for the anti-sex difference writers. The most important tactic is a comically biased, utterly non-representative view of the enormous literature of studies ranging from humans to single neurons. Other tactics include magnifying or inventing problems with disfavored studies, ignoring even fatal problems with favored studies, dismissing what powerful animal research reveals about mammalian brains, hiding uncomfortable facts in footnotes, pretending not to be denying biologically based sex-influences on the brain while doing everything possible to deny them, pretending to be in favor of understanding sex differences in medical contexts yet never offering a single specific research example why the issue is important for medicine, treating “brain plasticity” as a magic talisman with no limitations that can explain away sex differences, presenting a distorted view of the “stereotype” literature and what it really suggests, and resurrecting 19th century arguments almost no modern neuroscientist knows of, or cares about. Finally, use a catchy name to slander those who dare to be good scientists and investigate potential sex influences in their research despite the profound biases against the topic (“neurosexists!”). These tactics work quite well with those who know little or nothing about the neuroscience.

The book is downright farcical when it comes to modern animal research, simply ignoring the vast majority of it. The enormous power of animal research, of course, is that it can establish sex influences in particular on mammalian brain function (such as sex differences in risk-taking, play behavior, and responses to social defeat as just three examples) that cannot be explained by human culture, (although they may well be influenced in humans by culture.) Rippon engages in what is effectively a denial of evolution, implying to her reader that we should ignore the profound implications of animal research (“Not those bloody monkeys again!”) when trying to understand sex influences on the human brain. She is right only if you believe evolution in humans stopped at the neck.

Rippon tries to convince you (and may even believe herself) that it is impossible to disentangle biology from culture when investigating sex differences in humans. This is false. I encourage the interested reader to see the discussion of the excellent work doing exactly this by a sociologist named J. Richard Udry in an article I wrote in 2014 for the Dana Foundation’s “Cerebrum,” free online.

Rippon does not mention Udry’s work, or its essential replication by Udry’s harshest critic, a leading sociologist who has described herself as a “feminist” who now “wrestles” with testosterone. (The Dana paper “Equal ≠ Same” also deconstructs the specious “brain plasticity” argument on which Rippon’s narrative heavily rests.)

Of course, Rippon is completely correct in arguing that neuroscientists (and the general public) should remember that “nature” interacts with “nurture,” and should not run wild with implications of sex difference findings for brain function and behavior. We must also reject the illogical conclusion that sex influences on the brain will mean that women are superior, or that men are superior. I genuinely do not know a single neuroscientist who disagrees with these arguments. But she studiously avoids an equally important truth: That neuroscientists should not deny that biologically-based sex differences exist and likely have important implications for understanding brain function and behavior, nor should they fear investigating them.

You may ask: What exactly are people like Rippon so afraid of? She cites potential misuse of the findings for sexist ends, which has surface plausibility. But by that logic we should also stop studying, for example, genetics. The potential to misuse new knowledge has been around since we discovered fire and invented the wheel. It is not a valid argument for remaining ignorant.

After almost 20 years of hearing the same invalid arguments (like Bill Murray in “Groundhog Day” waking up to the same song every day), I have come to see clearly that the real problem is a deeply ingrained, implicit, very powerful yet 100 percent false assumption that if women and men are to be considered “equal,” they have to be “the same.” Conversely, the argument goes, if neuroscience shows that women and men are not the same on average, then it somehow shows that they are not equal on average. Although this assumption is false, it still creates fear of sex differences in those operating on it. Ironically, forced sameness where two groups truly differ in some respect means forced inequality in that respect, exactly as we see in medicine today.

Women are not treated equally with men in biomedicine today because overwhelmingly they are still being treated the same as men (although this is finally changing). Yet astoundingly, and despite claiming she is not anti-sex difference, Rippon says “perhaps we should just stop looking for [sex] differences altogether?” Such dumbfounding statements from a nominal expert make me truly wonder whether the Rippons of the world even realize that, by constantly denying and trivializing and even vilifying research into biologically-based sex influences on the brain they are in fact advocating for biomedical research to retain its male subject-dominated status quo so disproportionately harmful to women.

So are female and male brains the same or different? We now know that the correct answer is “yes”: They are the same or similar on average in many respects, and they are different, a little to a lot, on average in many other respects. The neuroscience behind this conclusion is now remarkably robust, and not only won’t be going away, it will only grow. And yes, we, of course, must explore sex influences responsibly, as with all science. Sadly, the anti-sex difference folks will doubtless continue their ideological attacks on the field and the scientists in it.

Thus one can at present only implore thinking individuals to be wary of ideologues on both sides of the sex difference issue — those who want to convince you that men and women are always as different as Mars and Venus (and that perhaps God wants it that way), and those who want to convince you of the demonstrably false idea that the brains of women and men are for all practical purposes the same (“unisex”), that all differences between women and men are really due to an arbitrary culture (a “gendered world”), and that you are essentially a bad person if you disagree.

No one seems to have a problem accepting that, on average, male and female bodies differ in many, many ways. Why is it surprising or unacceptable that this is true for the part of our body that we call “brain”? Marie Curie said, “Nothing in life is to be feared, it is only to be understood. Now is the time to understand more, so that we may fear less.” Her sage advice applies perfectly to discussions about the neuroscience of sex differences in 2019.

Larry Cahill is a professor in the Department of Neurobiology and Behavior at the University of California, Irvine and an internationally recognized leader on the topic of sex influences on brain function.

Footnote:  This video uses humor to look at sexual brains based on observed human behavior “Why Men and Women Think Differently.)

See Also Gender Ideology and Science, including excerpts from Jordan Peterson

Ralph B. Alexander writes at his blog Science Under Attack Belief in Catastrophic Climate Change as Misguided as Eugenics was 100 Years Ago. H/T Yen Makabenta Manila Times. Excerpts in italics with my bolds.

Last October’s landmark report by the UN’s IPCC (Intergovernmental Panel on Climate Change), which claims that global temperatures will reach catastrophic levels unless we take drastic measures to curtail climate change by 2030, is as misguided as eugenics was 100 years ago. Eugenics was the shameful but little-known episode in the early 20th century characterized by the sterilization of hundreds of thousands of people considered genetically inferior, especially the mentally ill, the physically handicapped, minorities and the poor.

Although ill-conceived and even falsified as a scientific theory in 1917, eugenics became a mainstream belief with an enormous worldwide following that included not only scientists and academics, but also politicians of all parties, clergymen and luminaries such as U.S. President Teddy Roosevelt and famed playwright George Bernard Shaw. In the U.S., where the eugenics movement was generously funded by organizations such as the Rockefeller Foundation, a total of 27 states had passed compulsory sterilization laws by 1935 – as had many European countries.

Eugenics only fell into disrepute with the discovery after World War II of the horrors perpetrated by the Nazi regime in Germany, including the holocaust as well as more than 400,000 people sterilized against their will. The subsequent global recognition of human rights declared eugenics to be a crime against humanity.

The so-called science of catastrophic climate change is equally misguided. Whereas modern eugenics stemmed from misinterpretation of Mendel’s genetics and Darwin’s theory of evolution, the notion of impending climate disaster results from misrepresentation of the actual empirical evidence for a substantial human contribution to global warming, which is shaky at best.

Instead of the horrors of eugenics, the narrative of catastrophic anthropogenic (human-caused) global warming conjures up the imaginary horrors of a world too hot to live in. The new IPCC report paints a grim picture of searing yearly heatwaves, food shortages and coastal flooding that will displace 50 million people, unless draconian action is initiated soon to curb emissions of greenhouse gases from the burning of fossil fuels. Above all, insists the IPCC, an unprecedented transformation of the world’s economy is urgently needed to avoid the most serious damage from climate change.

But such talk is utter nonsense. First, the belief that we know enough about climate to control the earth’s thermostat is preposterously unscientific. Climate science is still in its infancy and, despite all our spectacular advances in science and technology, we still have only a rudimentary scientific understanding of climate. The very idea that we can regulate the global temperature to within 0.9 degrees Fahrenheit (0.5 degrees Celsius) through our own actions is absurd.

Second, the whole political narrative about greenhouse gases and dangerous anthropogenic warming depends on faulty computer climate models that were unable to predict the recent slowdown in global warming, among other failings. The models are based on theoretical assumptions; science, however, takes its cue from observational evidence. To pretend that current computer models represent the real world is sheer arrogance on our part.

And third, the empirical climate data that is available has been exaggerated and manipulated by activist climate scientists. The land warming rates from 1975 to 2015 calculated by NOAA (the U.S. National Oceanic and Atmospheric Administration) are distinctly higher than those calculated by the other two principal guardians of the world’s temperature data. Critics have accused the agency of exaggerating global warming by excessively cooling the past and warming the present, suggesting politically motivated efforts to generate data in support of catastrophic human-caused warming.

Source: Tony Heller, Real Climate Science

Exaggeration also shows up in the setting of new records for the “hottest year ever” –declarations deliberately designed to raise alarm. But when the global temperature is currently creeping upwards at the rate of only a few hundredths of a degree every 10 years, the establishment of new records is unsurprising. If the previous record has been set in the last 10 or 20 years, a high temperature that is only several hundredths of a degree above the old record will set a new one.

Eugenics too was rooted in unjustified human hubris, false science, and exaggeration in its methodology. Just like eugenics, belief in apocalyptic climate change and in the dire prognostications of the IPCC will one day be abandoned also.

Ralph B. Alexander is a retired physicist and a science writer who puts science above political correctness. He is the author of Science Under Attack: The Age of Unreason and Global Warming False Alarm. Ralph grew up in Perth, Western Australia and received his PhD in physics from the University of Oxford.  Dr. Alexander has held a variety of positions in research, academia and industry over the course of his scientific career, and now lives in California. 

See also:  On the Hubris of Climatism

Control Population, Control the Climate. Not.

“Hottest Year” Misdirection

Man Made Warming from Adjusting Data