Is Sexual Offending Genetic?


Do genes make sex offenders? Are rapists and child molesters driven by biology or environment?

An article published last week in the International Journal of Epidemiology provides compelling evidence for a genetic component to risk of sexual offending.[1] The study found that sons or brothers of convicted sex offenders are 4 to 5 times more likely than randomly selected males to be convicted of a sexual offence. Half-brothers of sex offenders, in contrast, are only twice as likely as controls to be convicted of such offences. The study estimates on this basis that genetic factors contribute about 40% of this variability in risk of offending. Environmental factors shared between siblings, such as parental attitudes, were estimated to contribute only 2% of this variability. Continue reading

Editing the germline – a time for reason, not emotion

Gyngell, Douglas, Savulescu

There are rumours in the scientific community that the first studies involving the genetic modification of a human embryo are about to be published.[1] If true this would be the first case of an experiment in which genes in germ cells (sperm and egg cells) have been intentionally modified.  This has caused some concerns in the scientific community due to the fact that these modification are potentially heritable.  A commentary in Nature, (written by four leading scientists and one philosopher) published an appeal that we “Don’t edit the human germ line”.  Science meanwhile published a commentary which outlines “A prudent path forward for genomic engineering and germline gene modification”. The fact that two of the world’s most prestigious journals are publishing commentaries on human genetic modification shows just how powerful gene editing techniques have become. The rapid speed with which these technologies have developed has taken the scientific community, and everyone else, by surprise. Just three years after the DNA cutting nuclease Cas-9 was first used to modify DNA, scientists have been able to make heritable modifications to yeast, plants, mice, rats, pigs and even primates. It has been claimed that experiments conducted in China, currently under review, have used these same technologies to modify the DNA of human embryos.[2] Continue reading

The discussion that the scientists in Nature and Science called for should remain in realism, not go on to superhumans

Just over a week ago, prominent scientists in Nature and Science called for a ban for DNA modification in human embryos. This is because the scientists presume that now it actually would be possible to alter the genome in a human embryo in order to treat genetic diseases. Consequently, this would result in modified DNA in germ cells that would be inherited to future generations. The scientists wish to have a full ethical, legal, and public discussion before any germ-line modifications will be made. Furthermore, issues of safety are of importance.

The scientists’ statement is of utmost importance and hopefully this ethical, legal, and public discussion will emerge. However, the discussion on germ-line DNA modification is at danger if the debate will be taken to the level of science fictional superhumans, as already has happen. Not only can such discussion cause unnecessary public worry, it also leads the deliberation away from the actual and urgent questions.

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Born this way? Selecting for sexual preference

Doctors Offering ‘Gay Gene’ To Same Sex Couples Wanting Gay Children: apparently Dr. William Strider at the Fertility Center of Chicago suggests that homosexual parents should have the option of increasing the chances of their kid being homosexual:

“When straight couples have children, the majority of them want their children to be straight as well. That is why most straight parents have trouble accepting it when their children announce to them that they are gay,” …  “So it only makes sense that same-sex couples would want children that carried out their same family values of homosexuality.”

The article is likely reporting wrong on what method would be used: germline manipulation sounds like a unproven and risky approach, while PGD is a proven technique that could presumably select based on X-chromosome sequence. And given the topic it is not implausible that Dr. Strider is being misquoted. But let’s take everything at face value: would it be ethical to select for sexual preference?

Biomedical enhancement and the need for more precise conceptions

Much of the discussion about biomedical enhancements is about arguing whether some biomedical enhancement would, or would not be a good, ethical, or efficient means for enhancing a particular human characteristic. In this blog and in other bioethical literature bioethicists discuss the proposed effects that biomedical enhancements would have, for example, to intelligence and other cognitive capacities, empathy, sunny mood, altruism, sense of justice, or to halting climate change. The list is extensive and endless. The discussion on efficacy, ethics, justice, and human nature is an important part of the whole philosophical debate, as is the discussion about the limits of philosophy, reality, and science fiction. However, an important point that might be in need of emphasis would be to take under inspection the very concepts that are the target of enhancement. What do intelligence, sunny mood, altruism, sense of justice, and the-characteristics-that-prevents-us-halting-climate-change really mean?

If the target characteristics are looked at carefully, it seems that much of the discussion can be described as a form of language bewitchment where conceptions of the human language and conceptions of the empirical science of biology are mixed. Just because the human language includes conceptions such as intelligence, altruism, sunny mood, criminal, and sense of justice, it does not mean that there would be any corresponding concrete physical entities to these conceptions.

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The dappled causal world for psychiatric disorders: implications for psychiatric nosology

On Thursday 16th October, Professor Kenneth Kendler delivered his second (and final) Loebel Lecture, entitled ‘The dappled causal world for psychiatric disorders: implications for psychiatric nosology’. You can view it online here or listen here.

Whilst Kendler’s first lecture – summarised by Roger Crisp here – focused on empirical issues, the second lecture was more philosophical. Kendler’s key question in the second lecture could perhaps be formulated as: Given the complex aetiology of mental disorders, how can we best understand and explain how they arise? Continue reading

Iterated in vitro reproduction and genetic orphans

In an article soon to be published in the Journal of Medical Ethics, Rob Sparrow imagines a procedure via which multiple generations of human embryos might be created in the laboratory. Egg and sperm cells would first be generated from existing or new human pluripotent stem cell lines. The resulting eggs would be fertilised using the sperm to create zygotes and ultimately embryos. Embryonic stem cells would then be harvested from these embryos and used to create new egg and sperm cells, which would in turn be used to fertilise one another to create further embryos. This process could be iterated, in principle indefinitely.

Let’s call this procedure ‘iterated in vitro reproduction’ (Sparrow calls it ‘in vitro eugenics’). Iterated in vitro reproduction is not yet possible, but, citing recent developments in the science of stem cell-derived gametes, Sparrow argues that it may well become so, though he acknowledges are number of significant hurdles to its development. He also discusses a number of possible applications of the technology and calls for an ethical debate on these. The most controversial application would be in the creation of designer children. Consider the following case, which is a variant on one of the scenarios imagined by Sparrow:

Jack and Jill present to a fertility clinic. Jack provides a sperm sample, and fertility doctors harvest a number of eggs from Jill. These eggs are fertilized with Jack’s sperm to create embryos, from which embryonic stem cells are derived. These stem cells are then induced to develop into eggs or sperm which are used to fertilise one another, and so on. The process is iterated numerous times, and at each stage, the embryos are genetically screened via pre-implantation genetic diagnosis. This screening is used to inform a process of selective crossing, so that, over several generations, the population of embryos evolves towards certain genetic dispositions desired by Jack and Jill (a disposition towards longevity, say). This process is aided by adding small amounts of genetic material from stem cell lines derived from other individuals. Eventually, doctors identify an embryo with almost exactly the desired combination of genes, and this embryo is implanted into Jill’s womb and carried to term. A child, Jarvis, is born.

Cases like this raise numerous ethical issues, some of which are discussed by Sparrow and the seven commentators on his paper. However, they also raise an interesting conceptual question: would the users of such a technology be the genetic parents of the resulting offspring? Would Jack and Jill be the genetic parents of Jarvis?

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Bad news for “intelligence-genes”

Intelligence and its heritability has been a popular topic in scientific communities and public discussions for long. Recent findings give new insight to the debate: one of the largest studies on genetic influence to intelligence and other behavioral traits turned up inconclusive findings, as Nature News reports in a recent article “Smart genes” prove elusive.

Existing literature on candidate gene associations is rich in studies that have been unable to replicate and findings have been based on “wishful thinking and shoddy statistics”. According to an editorial in Behavior Genetics,

it now seems likely that many of the published findings of the last decade are wrong or misleading and have not contributed to real advances in knowledge. Continue reading

Lord Winston’s warning

Last month, Lord Robert Winston delivered the Physiological Society summer lecture entitled, ‘Shall we be human in the next century?’ You can watch it in full here (the stream starts working around 5”30 onwards). In the lecture, Lord Winston discusses the history and misuse of gene science and eugenics, and points to the potential resurgence of this way of thinking, made possible by advances that would allow us to genetically enhance human beings by modifying their nonpathological traits. Winston would be classified as a ‘bioconservative’ in the contemporary enhancement debate, and below I examine the case for caution that he puts forward in this lecture.

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Genetically Modifying Mosquitoes to ‘Bite the Dust’? Ethical Considerations

At some point, most people will have questioned the necessity of the existence of mosquitoes. In the UK at least, the things that might prompt us into such reflection are probably trivial; in my own case, the mild irritation of an itchy and unsightly swelling caused by a mosquito bite will normally lead me to rue the existence of these blood-sucking pests. Elsewhere though, mosquitoes lead to problems that are far from trivial; in Africa the Anopheles gambiae mosquito is the major vector of malaria, a disease that is estimated to kill more than 1 million people each year, most of whom are African children. Continue reading


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