Many Christian parents have asked me this question. They are struggling with a child who has recently “come out” and are trying to grapple with this new reality. These parents have lovingly taught their children the Bible, taken them to church all their young lives, and can’t understand how their children could possibly choose this sinful sexual behavior. They think biology may help explain what they are wrestling to explain any other way. So, can it? And if biology can explain it, is homosexual behavior still sinful if God made them that way?
An Evolutionary Dead End
From an evolutionary perspective, it really wouldn’t make any sense for homosexuality to have a biological basis. One of the major tenets of evolution is reproduction and passing on one’s genes to the next generation. As one author put it, “The existence of homosexuality amounts to a profound evolutionary mystery, since failing to pass on your genes means that your genetic fitness is a resounding zero.”1
And if homosexual behavior has a genetic component, how could it even be passed on to future generations? In many ways, it’s an evolutionary dead end. Some evolutionists have tried to explain it with the idea of kin selection. Even though homosexuals won’t pass on their genes, they help raise nieces and nephews who will have some of their genetic information. However, studies have shown no difference in how homosexual and heterosexual individuals treat their close relations, so this work-around seems to fall short.2
A Series of Inconclusive Studies
Historically speaking, the search for a biological explanation for homosexuality has been unsuccessful or at the very least inconclusive. Two prominent studies were those of geneticist Dean Hamer and neuroscientist Simon LeVay in the early 1990s. Hamer tried to show that a region on the X chromosome was linked to homosexuality.3 He suggested a gene or genes existed in that region that had variants more often associated with homosexual behavior. However, later scientists failed to find this linkage.4
LeVay looked to see if differences existed in the hypothalamus in the brain of homosexual men versus heterosexual men. He reported that a particular structure in the hypothalamus (known as INAH-3) was smaller in homosexual men.5 However, there were several problems with the study. The sample size was small, and the size of this region of the brain was in the same range for both homosexual and heterosexual men.
Two recent studies have once again shined the spotlight on possible biological causes for homosexuality but with still very inconclusive results. It’s important to remember that both studies assumed that sexual orientation has at least some measure of biological causation, which may or may not be the case.
One study found certain variations (known as single nucleotide polymorphisms—SNPs) in regions associated with two genes, SLITRK6 on chromosome 13 and TSHR on chromosome 14, were more commonly found in homosexual men.6 The proteins produced by these genes are involved in the development of the brain and thyroid cell metabolism, respectively.
However, it is unknown whether these proteins play any role in sexual orientation. Even the scientists who performed the research admitted there were problems with the study. For example, all of the participants were from one ancestral group (European), so the question arises whether these variants (SNPs) are just normal variations in people with that ancestry and not related to homosexuality. They also admit to having a small sample size, which may affect the results.
Another study looked at a possible biological cause for a supposed phenomenon that has been observed among homosexual men, known as the fraternal birth order effect.7 In summary, homosexual men tend to have more older brothers than heterosexual men. Why would this be? Some scientists proposed that the mother’s immune system develops antibodies against a protein important for the development of her male baby’s brain while in her womb.
If the mother’s body develops the ability to make antibodies against this protein when she is pregnant with her first son, when she becomes pregnant with subsequent sons, the antibodies will be produced and inhibit the actions of those proteins, making it more likely that these sons will exhibit homosexual behavior.
The study found that these mothers did, indeed, have high levels of antibodies that attack this protein (NLGN4Y). However, it found that mothers of gay sons with no older brothers also had high levels of these antibodies, so the result seems inconclusive at best. The sample size was also small.
Even the authors themselves admitted they don’t know how this protein might have a role in determining behavior. They stated, “It is not certain how NLGN4Y might operate at the cellular level on the neuropsychology of men’s sexual orientation” and “sexual orientation is clearly a complex phenomenon with likely many factors influencing it.”
Both past and present scientific studies have shown no conclusive evidence that homosexual behavior is biological; and even if there is a biological basis, the researchers themselves admit that it would likely make a relatively small contribution (less than one-third if at all, with the environment and other cultural factors having a much greater influence).
The Root Problem Is Not Biology
In many ways, the attempt to tie behavior to biology is an effort to normalize sin and remove responsibility for people’s feelings and actions. The idea of genetic determinism is rampant and important in evolutionary thought, as humans would have to be nothing more than “matter in motion” with no soul and merely the preprogrammed product of their genes.
Starting with a biblical worldview, we know that we are made in the image of God and have a soul. We are much more than just the sum of our genes.
However, starting with a biblical worldview, we know that we are made in the image of God (Genesis 1:27) and have a soul (Matthew 16:26, 22:37). We are much more than the sum of our genes. We also know that we have a will and can make choices for or against God (Joshua 24:15; Matthew 12:30). God’s Word makes it clear that homosexual behavior is sinful (Romans 1:26–28; 1 Timothy 1:9–11; 1 Corinthians 6:9–11) but so are many other things like alcoholism, drug addiction, promiscuity, lying, cheating, stealing, and many other sins. If a gene was found that made it harder for people not to commit adultery, would that excuse adulterers who were born that way?
Ever since Adam’s rebellion, all of us are born sinners (Psalm 51:5), and all of us struggle with sin, but we must remember, “No temptation has overtaken you that is not common to man. God is faithful, and he will not let you be tempted beyond your ability, but with the temptation he will also provide the way of escape, that you may be able to endure it” (1 Corinthians 10:13).