Tag Archives: gene

The Gay Gene Re-Visited

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 But this method – known as the linkage method – has been found to be deficient in many ways and it has since been superseded by another method known as genome-wide association (GWA).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


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.

Obligation to Future Generations

January 2016 Pulse

One of the most significant and yet controversial developments in genetic science in recent decades is the Human Germline Genetic Modification (HGGM) technology. By employing a set of techniques, scientists hope to be able to change the genetic composition of the human germline (i.e., eggs, sperm, the cells that give rise to eggs and sperm, or early embryo) for the benefit of future descendents who will inherit them.

The main purpose of HGGM is to ‘cleanse’ the gene pool of ‘deleterious’ and inheritable genes that would predispose people to certain diseases. This approach, according to some scientists, is to be preferred to traditional therapeutic strategies. For example, molecular biologist Daniel E. Koshland, Jr. could argue that ‘keeping diabetics alive with insulin, which increases the propagation of an inherited disease, seems justified only if one ultimately is willing to do genetic engineering to remove diabetes from the germline and thus save the anguish and cost to millions’.

The ultimate goal of HGGM is therefore to eradicate harmful genes responsible for diseases like cystic fibrosis from the whole population.

In this sense, HGGM must be distinguished from somatic cell therapy that involves the genetic modification of cells in the body apart from the reproductive cells. Somatic cell therapy treats the person with a genetic disease in a way that does not affect his or her offspring. While there is currently an international moratorium on HGGM, many countries in the world allow somatic cell therapy.

Although it is the intention of many scientists to use HGGM for therapeutic purposes, some are advocating that it should also be used to enhance certain desirable traits in the future generation. While many theologians and ethicists are opposed to this, the debate is complexified by the fact that the distinction between eliminating harmful genes and improving hereditary is very often blurred.

The main concern about HGGM is safety. Because these techniques edit the genetic makeup of the gametes, the changes inherited by future generations are deemed irreversible. Thus, the European Council for the Protection of Human Dignity states in its 1997 document that ‘Whilst developments in this field may lead to great benefit for humanity, misuse of these developments may endanger not only the individual but the species itself’.

Many scientists and ethicists maintain that it is simply impossible to envision the consequences of HGGM at this point. The debate sometimes gravitates to the question about the acceptable criteria for ascertaining whether it would be safe to proceed with HGGM. Although the current standard and protocol for research states that an intervention is considered adequate if it enjoys 70% success, some are arguing (for obvious reasons) that in the case of HGGM the requirement should be no less than a success rate of 100%.

In 1979, the influential philosopher and ethicist Hans Jonas in his remarkable book, The Imperative of Responsibility reminded us that in the midst of the tantalising progress of science and technology we must always pause to consider our responsibility to the future generation. The advance of science should not only fill society with a sense of hope, Jonas argues. It should also fill us with a sense of fear.

It is only when fear has its rightful place in our reflections on the promises of science and technology, he wisely counsels, that we will come to see that the ‘starry-eyed ethics of perfectibility has to give way to the sterner one of responsibility’.

Because the long-term adverse consequences of HGGM for future generations are not yet known or fully understood by scientists, and in light of the ethics of responsibility that Jonas emphatically advocates, both religious and secular institutions are opposed to the use of this technology on humans.

Dignitatis Personae, issued by the Roman Catholic Church in 2009, states that ‘Because the risks connected to any genetic manipulation are considerable and as yet not fully controllable, in the present state of research, it is not morally permissible to act in a way that may cause harm to the resulting progeny’.

This is echoed in a statement on HGGM issued by the United Methodist Church in 2012, which states quite categorically that ‘We oppose human germ-line therapies (those that result in changes that can be passed to offspring) because of the possibility of unintended consequences and of abuse’.

‘With current technology’, it continues, ‘it is not possible to know if artificially introduced genes will have unexpected or delayed long-term effects not identifiable until the genes have been dispersed in the population’.

In similar vein, the International Society for Stem Cell Research (ISSCR) calls for a moratorium on HGGM in a statement issued in 2015: ‘The ISSCR calls for a moratorium on attempts to apply nuclear genome editing of the human germ line in clinical practice. Scientists currently lack an adequate understanding of the safety and potential long-term risks of germ line genome modification’.

The call to acknowledge our responsibility towards future generations serves to remind us that no human being – present or future – should be excluded from our moral community or moral consideration. It must therefore be taken very seriously.


Dr Roland Chia


Dr Roland Chia is Chew Hock Hin Professor of Christian Doctrine at Trinity Theological College and Theological and Research Advisor of the Ethos Institute for Public Christianity.