December 2016 Pulse
In 2014 Alan Sanders, a Clinical Associate Professor of Psychiatry at Northwestern University at Evanston, and his team conducted a study of 409 pairs of twin brothers to see if there are some linkages between homosexuality and chromosomal region Xq28.
This study – the largest to be undertaken to date – attempts to validate the results obtained by a study by Dean Hamer and his team of scientists in 1993 at the National Cancer Institute in the United States. Working with only 40 pairs of homosexual brothers, Hamer and his team discovered that 33 pairs (or 83%) had the same sequence of markers in the X chromosome region known as Xq28.
This had led Hamer to conclude that ‘One form of homosexuality is preferentially transmitted through the maternal side and is generally linked to chromosomal region Xq28’.
To their surprise, Sanders and his team – which included J. Michael Bailey, who together with Richard Pillard, conducted the famous twin study – found the same linkages between homosexuality and the chromosomal region Xq28 suggested by the earlier study by Hamer.
Hamer was understandably delighted with the findings of the Sanders study. ‘Twenty years is a long wait for validation’, he is reported to have said, ‘but now it’s clear the original results were right. It’s very nice to see it confirmed’.
However, like the Hamer study in 1993, the Sanders study of 2014 failed to establish conclusively the genetic determinant for homosexual orientation.
Sanders used the same method that Hamer employed twenty years ago in order to replicate Hamer’s study. But this method – known as the linkage method – has been found to be deficient in many ways and it has since been superseded by another method known as genome-wide association (GWA). Sanders himself acknowledged the fact that GWA studies are far more superior to genetic-linkage studies.
Although Sanders was able to confirm the link between homosexuality and the chromosomal region Xq28, the causative or correlative relationship between them is never established, making this finding insignificant. Thus, a number of researchers and scientists such as Neil Risch have pointed out the findings of both the Hamer and Sanders studies are statistically insignificant.
In fact, Sanders himself acknowledged that the findings have not crossed the threshold of significance. He further stated that even though he believes that Xq28 has something to do with homosexuality, a trait as complex as sexual orientation depends on many factors, genetic and nongenetic alike.
Geneticists have long understood that the exact relationship between the genotype and the phenotype is very difficult to establish. The genotype refers to the set of genes in the DNA that is associated with a particular trait, while the phenotype is the actual expression of that trait.
Many geneticists maintain that the relationship between the two is never straightforward and warn against a naïve ‘genetic determinism’ that refuses to recognise the complexities. In fact, many would argue that the genotype typically undermines the phenotype.
With the advance of the field of epigenetics, scientists are beginning to see the importance of the interaction of the genes with their immediate cellular environment as well as the external environment. In addition, intrauterine influences (which includes nongenetic factors) as well as extrauterine influences also play their part.
Life experiences also play a significant role in forging a particular trait, especially one as complicated as sexual preference and behaviour. Experiences that were had in the early stages of one’s personal development are deemed especially important.
As Frances Campaigne of Columbia University puts it: ‘Social experiences throughout life influence gene expression and behaviour, however, early in development these influences have a profound effect’.
The Sanders study has left all these other aspects unexplored and the questions they raise unanswered.
Although science is important in our attempt to understand human sexual preferences and behaviour, for the Christian it cannot have the last word. Thus, even if science is able to discover the genetic basis for homosexual orientation, the Christian cannot on that premise alone conclude that homosexual behaviour is natural and therefore must not be prohibited.
For the Christian, it is the mystery of human sexuality that Scripture reveals that should serve as the basis for sexual behaviour. In our fallen world, supposedly ‘innate’ impulses cannot be indicative of what is natural – that is, what is intended by the Creator – even if the genetic or neurological determinants of these impulses are ascertained.
For the Christian, sexual conduct must be ordered according to the way in which human sexuality has been designed and purposed by the Creator. And according to the Bible, the only legitimate form of sexual activity is between a man and a woman, and the only legitimate context for such activity is the covenant of marriage.
It is in light of God’s design of and purpose for human sexuality that all other forms of sexual behaviour and activity – fornication, adultery, incest, prostitution and bestiality – are not only strictly prohibited, but are also often regarded as abominations.
This means that the meaning of human sexuality is too complex and multifaceted for science to unravel. It has to do not only with biology, but also morality. It has to do not only with impulses and emotions, but also ontology. It has to do not only with the individual, but also and more fundamentally with the ordering of our familial and social lives in a way that is harmonious with God’s design and intention.
In a word, human sexuality is too profound a reality to be left to science alone.
Dr Roland Chia is Chew Hock Hin Professor of Christian Doctrine at Trinity Theological College and Theological and Research Advisor for the Ethos Institute for Public Christianity.