A Look at What the Research Shows and What It Means for You
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A look at what the research shows and what it means for you JEFF JOHNSTON INTRODUCTION Introduction 2 In 1992, Newsweek The Wall Street Journal, and The New York Times magazine’s cover trumpeted the possibility that people were “born pictured a baby’s gay” because of a “gay gene.” Is There a “Gay Gene”? 3 face with a question superimposed More than 20 years later, a great deal of research Didn’t Researcher on top: “Is This has been done, and despite the hype from different Dean Hamer Discover Child Gay?” The news outlets: a “Gay Gene”? 4 article inside was titled, “Born or ■ there is no “gay gene”; What Do Twin Studies Show? 7 Bred: The Origins of Homosexuality.”1 ■ twin studies show homosexuality Newsweek is primarily environmental; and, Do Some People Source: BackIssues.com highlighted the Have “Gay Brains”? 9 ■ homosexuality is not caused by a “gay brain.” work of researcher Simon LeVay, whose research showed a tiny part of the hypothalamus was So, we can say with a great deal of confidence: What Conclusions can we different in homosexual-identified males than People are not “born gay.” Draw from The Research? 11 in heterosexual males.2 The story also reported on the work of Michael Bailey and Richard Let’s look at each of these areas of research in Pillard, who studied the shared incidence of male turn, and also answer a few more questions about What Does This Mean to You? 12 homosexuality in identical twins versus the shared homosexuality. incidence in fraternal twins or in brothers.3 The next year, Time magazine featured a cover “Complex social activities, such story, “Born Gay: Science Finds a Genetic Link.”4 as sexual behavior, cannot be Researcher Dean Hamer had published an article directly traced to the activity of demonstrating there might be “…linkage between a single gene.” DNA markers on the X chromosome and male sexual orientation.”5 Time also spotlighted the work —Dr. Douglas Abbott 6 of LeVay, Bailey and Pillard. Major news outlets in the early 90’s, such as National Public Radio, ARE PEOPLE BORN GAY? 2 IS THERE A Each human has 46 chromosomes, 23 pairs, with one of each pair inherited from mom and the other from “GAY GENE”? dad. In their book (with the tongue-in-cheek title) My Maybe you’ve read about Gregor Mendel, the Genes Made Me Do It! A Scientific Look at Sexual Moravian monk and scientist who studied peas by Orientation, Dr. Neil and Briar Whitehead write: breeding them for a certain trait and then cross- pollinating “Each chromosome is made up of one highly them with folded strand of deoxyribonucleic acid (DNA) other peas made up of an extraordinary twisted ladder with a of 60 to 185 million rungs depending on the different chromosome. If you joined, end to end, each trait. Mendel unfolded, untwisted chromosome in a single cell, conceived you’d have about three billion rungs.”7 and developed Each chromosome is made up of genes, which the ideas of are shorter sections of DNA “in a particular location recessive on a specific chromosome,” carrying instructions and about making different proteins or about activating dominant or deactivating other genes. Each of us has traits and somewhere between 20,000 and 25,000 genes, worked to and each gene has anywhere from 1,400 to decipher how 4,000 rungs.8 traits are passed from The Whiteheads paint a picture of the incredible parent plants God-designed complexity of genes at the beginning Source: Time.com, Cover Credit: STEVE LISS to offspring. of a human life, as they describe the activity in a single-cell human embryo: While Mendelian ideas work well on some traits in plants and on some physical traits in humans, such “Biochemists themselves rarely appreciate how as eye or hair color, human genetics is much more complex a single cell is. To use a metaphor: one complex. It’s inaccurate to say that a single gene single fertilized ovum, for example, resembles a causes a certain behavior. vast plain crammed with about a billion dancing ARE PEOPLE BORN GAY? 3 figures on a complex grid, either spinning “The simple world of monk Gregor alone or briefly forming long chains or small Mendel and his peas—in which groups or circles, only to break away and form single traits like tallness, colour and thousands of others. There are about one billion seed shape are each determined by a biochemical reactions each second (plus or single gene—is almost never seen in minus a factor of ten) within this single cell—a human genetics.” dazzlingly complex mesh of actions, interactions, —Dr. Neil Whitehead and Briar reactions, feedback and control paths, and co- Whitehead, “My Genes Made Me Do It!” 10 operation and interference, causing thousands of genes, and all the gene products within the cell, to interact. More than 100 trillion other cells Most scientists who study genetics know that in this potential human body have yet to only a portion of how we behave is affected by develop in the same way and begin genes. Other determining factors include our to interact with each other in this environment—the family and culture we are extraordinary dance of life.”9 born into—and our decisions, the choices we make with our will. We’ll talk more about that later As the Psalmist says, in this resource. Adenine God’s works are wonderful, and we are Guanine fearfully and wonderfully made (Psalm DIDN’T RESEARCHER Cytosine 139:4, ESV). DEAN HAMER Thymine Most genes don’t act DISCOVER A independently: They are activated and affected by “GAY GENE”? other genes, as well as by other factors and chemicals in In 1993, researcher Dean Hamer performed what the body. Our genes are what make is called a “linkage study” for behavior: us human—they cause our bodies to be formed and grow in certain ways. So all human “In linkage studies for behavior, researchers look behavior, to some degree, is affected by genes. for an extended family with an unusually high ARE PEOPLE BORN GAY? 4 incidence of some behavior, such as bipolar however, when researchers tried to replicate disorder, and then take samples of tissue from all the initial findings, they were unable to do so. available members and analyze the DNA, looking Sometimes researchers reanalyzed the results and for segments in common using sets of tiny, came to a different conclusion. Other times they synthesized DNA segments, called ‘markers’— found the link was not as strong as first reported. an identical set for each person.”12 Here’s what Robert Pool wrote in Science, in the same issue that published Hamer’s study, signaling Hamer and his team that the results should be received with caution: “Any dispassionate but critical looked at 40 families review of the research leads to with two gay-identified “The field of behavioral genetics is littered with the clear conclusion that there brothers in each family. apparent discoveries that were later called into are substantial genetic and He also studied their question or retracted. Over the past few years, environmental effects on almost all extended families and several groups of researchers have reported types of behaviour and all forms found more homosexual- locating genes for various mental illnesses—manic of psychopathology or mental identified relatives on depression, schizophrenia, alcoholism—only to disorder…. None of the findings are the mother’s side of the see their evidence evaporate after they assembled in the least bit compatible with a family, leading him to more evidence or reanalyzed the original data. genetically deterministic view.” suspect a genetic link ‘There’s almost no finding that would be convincing —Sir Michael Rutter, on the X chromosome. by itself in this field,’ notes Elliot Gershon, chief of “Genes and Behavior” 11 The X chromosome the clinical neurogenetics branch of the National comes from the mother; Institute of Mental Health. ‘We really have to see the Y chromosome an independent replication.’”13 comes from the father. Hamer found that 33 of the pairs of brothers shared five markers on their These problems were true of Hamer’s work. One X chromosome at a position on the chromosome Canadian research team tried to replicate Hamer’s known as “Xq28.” findings using a larger sample of 52 gay-identified sibling pairs from 48 families. The team looked for Although scientists have found genes for numerous markers at the same site, Xq28, and said, “Allele physical conditions, they have not had the same and haplotype sharing for these markers was success in finding genetic markers for behaviors. not increased over expectation. These results do In many cases, researchers or the press have not support an X-linked gene underlying male announced a possible genetic cause for a behavior; homosexuality.”14 ARE PEOPLE BORN GAY? 5 Not only was Hamer’s “There is a clear consensus among sexual orientation, as it work not replicated in scientists that a gay gene does does in most, if not all other studies, it was not exist. Complex psychosocial behaviors…”17 critiqued because there behaviors, such as sexual was no control group. orientation, cannot be directly Later in the book, Perhaps other men who traced to the activity of a single he writes: didn’t identify as gay had gene or even a group of genes.” the same genetic markers “The pedigree study on their X chromosome. —Douglas A. Abbott and failed to produce what The study was also A. Dean Byrd, “Encouraging we originally hope to 16 criticized because of lack Heterosexuality” find: simple Mendelian of statistical significance inheritance.