Designer Babies are finally here, thanks to the good folks at The Fertility Institutes.

In the latest twist in the march towards designer babies, The Fertility Institutes says they will soon be able to offer couples the ability to screen their embryos for eye color, hair color, and complexion.  The Institute cannot change the DNA of the donating couple — if neither the mother nor the father has genes for green eyes, for example, then the Institute cannot give them a baby with green eyes.  Yet within the constraints inherent in the DNA of the donating couple, The Fertility Institute is willing to screen embryos for these traits.  The Fertility Institute wants to offer several other customizations, and many more are sure to be released in the coming years as the science behind screening for them is developed.

Here in New Zealand the law has been found to allow the use of PGD in preventing serious disease.  I have a variety of small and not-so-small genetic health problems, and I’ve always thought that fixing these things up before I was more than a few cells wide would have been a real boon.

I do see a small ethical problem here, which is that one isn’t improving (or creating from scratch) one embryo, but producing several and screening them for the desired (and undesired) traits.  I think a one-embryo solution would be more ethically acceptable.

Apart from that, there is another potentially thorny issue to consider.  If homosexuality is a genetically-influenced trait, and you had control over which genes your child was given, would you make a decision regarding your child’s potential sexuality?

I tackled exactly this question a few years ago in an essay for the my 3rd year Molecular Genetics paper.  I’d be interested to hear your thoughts.

The essay follows after the break.

Homosexuality:  A Choice For Your Child?

Greg Egan is an Australian science fiction author who has written many critically-aclaimed stories, many focusing on the effect of future biotechnology advances on moral and ethical issues.  His short story anthology Luminous includes one such story ‘Cocoon‘.

Cocoon

A private detective wakes at four in the morning with a new case file: an explosion which destroyed Life Enhancement International’s biotechnology research laboratory. The cause is a bomb, but the motive is unclear. The lab was working on a genetic treatment to improve the maternal-embryonic blood barrier in the placenta to prevent the passage of viruses, toxins, pharmaceuticals and illict drugs from mother to child. Who could object to an attempt to protect unborn children from HIV, thalidomide-type drugs and cocaine addiction?

Next is is discovered that the back-up cultures that the company kept at a separate location have been destroyed by slow irradiation – someone is going to a lot of effort to stop this research. Then is revealed that the improvement to the placental barrier prevents maternal hormones from affecting the sexual orientation of the fetus – effectively ensuring heterosexual children to users of the treatment. An organisation of homosexuals has been attempting to bring the research to public attention, but they did no violence. Life Enhancement International has set up the destruction of its lab and some of the backup materials in order to frame this group and turn public opinion against homosexuals, reasoning that a homophobic backlash will help sell their treatment to ensure heterosexuality. The story ends with our hero, having figured out this horrendous scheme, pondering the dilemma.

“That’s what I’d missed … you can’t sell a cure without a disease. … Even if there was nothing left but heterosexuality in a century’s time, the only path which could lead there would be one of lies, and wounding, and vilification. Would people buy that or not? I was suddenly very much afraid that they would.”

Sexual Orientation

Egan’s chilling story is a passionate exploration of the ‘normalness’ of homosexuality. Is it an abnormality, wiped away without a thought? Or a lifestyle choice to be proud of, and to fight for? The politically correct answer today is that homosexuality is normal and natural. Yet it was only in 1973 that homosexuality was removed as a disorder from the Diagnostic and Statistical Manual used by psychologists.

To discuss the ethical dilemma of determining the sexual orientation of our children, I will first start with exploring sexual orientation.

More than 90% of the human population are heterosexual, that is, they are sexually attracted to the opposite sex. Approximately 5-7% of the population is homosexual, that is, they are sexually attracted to members of their own sex. And less than 5% are bisexual, and can become attracted to people of either sex.

Sexual orientation is now accepted to be a fixed behavioural trait in humans before birth. Studies have correlated homosexuality with fingerprint and finger length differences which are set before birth, suggesting that sexual orientation is set before the 4th week of preganancy. And studies of pre-school children found that 75% of boys expressing ‘effeminate behaviour’ grew up to become homosexual.

Genetic Component of Male Homosexuality

Pedigree studies reveal a strong genetic component of homosexuality. Hamer et al (1993) examined the families of 76 homosexual men. Their 106 brothers were 13.5% homosexual, significantly higher than the incidence in the general population.

Whitam, Diamond and Martin (1993) examined 61 homosexuals who had twins. Of the identical twins, 64.7% were also homosexual. Of the fraternal twins, 28.6% were homosexual.

Similarly Bailey and Pillard (1991) found identical twin concordance to be 52%, amd fraternal twin concordance to be 22%. Studies on raised-apart siblings and twins revealed similar results, discounting an upbringing factor.

These results are very close in agreement, with some hypothesising a ‘homosexuality gene’ with a penetrance of around 67%. However there is still disagreement in this area. King and McDonald (1992) found concordance rates of just 12.5% among fraternal twins and 25% with identical twins.

Dean Hamer and his colleages, in “A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation” (Science 261 (July 16, 1993): pp 321-27) hypothesised that homosexuality was passed on through the maternal side (from observations in previous studies), suggesting a gene on the X chromosome was involved. Indeed, when the researchers examined markers on the X chromosome of 40 homosexual brothers they found that 33 of them shared a very similar region at Xq28. The research looked at 21 genetic markers on the X chromosome and identified 5 markers inside Xq28 as being highly correlated between the homosexual men, with none of the sixteen markers outside Xq28 being correlated at a statistically significant level. Hamer did not find a specific gene, only a region of the X chromosome (five-million base pairs, in fact) that was highly correlated between the homosexual men in his sample. This is strong evidence that some part of Xq28 forms part of the genetic basis for homosexuality. Such a controversial study has been criticised on various grounds: the statistical significance of the study rests on only 2% of the population being homosexual, rather smaller than generally accepted. Hamer has repeated the study and found a similar result, but other research has failed to find a significant linkage in the region amongst homosexual men.

Female homosexuality is not as intensively studied as male homosexuality but seems to be similarly genetically determined, albeit not using the same genes. Bailey and Pillard followed up their 1991 male homosexual research with a lesbian study in 1992, finding that there was a 6% chance of adopted sisters being both lesbian (approximately background probability), but both-lesbian fraternal twin sisters had a higher concordance at 16% and lastly found a 48% concordance between identical twin sisters.

Therefore it is concluded that homosexuality has a strong genetic basis. We can construct a tentative model for male homosexuality with a gene locus at the Xq28 region of the X chromosome creating a maternal-inherited gene with an approximately 67% penetrance. So while genes do not wholly determine homosexuality, it certainly has a strong influence. The maternal inheritance makes it difficult to separate out factors in the womb such as hormones, which have been implicated by a few researchers (Egan uses the maternal hormone interaction as the basis of caused homosexuality in ‘Cocoon’).

Designer Babies

A common idea raised when we talk about genetic engineering is the concept of ‘designer babies’. Choosing the genes that make up our offspring – selecting for increased intelligence, healthy bodies and attractive, athletic features. Selecting against or screening for genetic diseases like Huntington’s Chorea and Alzheimers disease. Its an attractive concept – many people have genetic diseases like asthma and bad eyesight that they wish their parents had removed before their birth.

That’s only a fictional scenario right now. Assembling a ‘perfect’ human genome that includes all the desirable genes a parent could choose, and eliminating and replacing deleterious ones, is far beyond any laboratory’s technical ability. But it is possible to screen embryos for various genes – such as alleles for Huntington’s Chorea mentioned above. Many families afflicted by these terrible illnesses have already chosen to test their offspring for various diseases with genetic screening before in vitro fertilisation, choosing only unaffected embryos for implantation.

But what if this genetic screening extended to the genes that influence homosexual behaviour? If they had to make a choice for their child, the majority of heterosexual parents would surely choose heterosexuality for their offspring – it would save them from homophobia, the increased risk of HIV in male homosexual populations, and the pain and embarrassment of finding out that one is different from the majority of people in the world.

What would you choose?

Assuming this genetic choice was widely available, it could potentially change the human population in just one or two generations. The number of homosexuals born could plummet until they were a tiny minority, less than 1% of the population. A bloodless extinction, a quiet coup by the heterosexual majority, making the choice for their children’s sexual orientation. Of course, homosexual couples conceiving children by artifical means could choose to give their children homosexual genes, too, and some heterosexual couples would leave it to chance. The extinction of homosexuality is only a worst-case scenario, but it illustrates the issue.

The ethical dilemma, then, is whether to give people the choice at all. Should we allow parents to decide whether to leave their childrens sexual orientation to chance, or choose the ‘default’ option of heterosexuality every time? Or on the other hand should laws be passed to prevent this choice from being offered – enforce the genetic possibility for homosexuality?

This scenario has not been widely discussed. Indeed, the source for this idea is fiction. But a genetic basis for homosexuality has been firmly established, and when genetic screening of our children is routine for many alleles, the possibility will be real enough. Clearly there will be groups fighting for either side of this ethical dilemma.

Pro-choice Groups

On the one hand, groups like fundamentalist Christians will want a chance to reduce the likelihood that their children will be homosexual. Many Christians believe that homosexuality is wrong in the eyes of God, and the option to ensure (or at least greatly improve the chances) that their children are heterosexual may be irresistable. Other couples may share a homophobic attitude and wish to try and ensure their children are heterosexual.

Other groups supporting the option of choice may be civil liberties groups, who might argue that parents have a moral responsibility to do everything within their power to ensure the wellbeing of their child. This might include treating illnesses, giving the child the best educational opportunities, and paying to get them into a good school. This argument could be logically extended to obtaining treatment to prevent Downs syndrome, Huntington’s disease or cancer mutation genes, if possible. Would this moral responsibility extend to giving a child a good genetic potential to begin with? Intelligence, good temperament, physical health and characteristics like height and attractiveness could all be argued to be an advantage for a child. What if parents feel that heterosexuality will also be an advantage? Is it then morally permissible for them to choose this for their child? Certainly this could be argued.

Pro-Homosexuality Groups

On the other side would be gay and lesbian advocate groups. The idea of being able to choose the sexual orientation of ones children might not be too popular amongst these groups if it threatens to dwindle the homosexual portion of the population (5% to 7%, by most estimates) potentially to nothing. Parents who make the choice might be branded homophobics; researches and labs who collobarate It is entirely possible that there might be terrorist action by homosexual groups against the possibility. These groups might argue that the basis of wanting to choose heterosexuality is inherently homophobic and biased in favour of heterosexuality. From a politically correct viewpoint, this would be as wrong as discriminating by race or gender.

Other groups against the choice might be those who believe that interfering in any natural process during reproduction is wrong, such as Greenpeace who oppose genetic engineering. Some Christian groups similarly oppose a wide range of biotechnology on the suggestion that it is ‘playing God’. If one believes that nature, fate or God determines the outcome of these processes, then it might be wrong for parents to interfere with the natural processes of genetic recombination and inheritance that occur in the absence of artificial deliberate allele selection.

Other arguments specifically in support of homosexuality might include promoting the increased diversity in society that gay and lesbian groups provide, and suggestions that homosexuals contribute more to society in terms of art, philosophy and writing, possibly because they spend less time and energy on reproduction and more time on these things.

Diversity in society is certainly to be encouraged. And if we really see homosexuality as a normal and natural sexuality variation, then there is certainly no reason to prevent our children from becoming homosexual. But if we allow parents to influence their children’s health, intelligence, athleticism, why can’t we give them the option to influence sexual preference? If we do, however, the number of homosexuals in the population could dwindle to a tiny minority.

Parental Rights

What the debate comes down to, then, is the right of parents to choose the genetic make-up of their prospective child. As legal guardians, parents are required to provide various basics of life: food, shelter, hygienic living conditions, protection from abuse. Parents who do not take their obviously sick child to a doctor can and have been prosecuted for negligence. If genetic tests and treatments become widely available and relatively cheap, could they be expected to do basic genetic screening – say, for Down’s syndrome or cystic fibrosis?

If it is decided that sexuality should not be subject to parental choice, laws might not be an effective way to enforce governmental policy. When people want something badly enough, they will find a way to do it: private laboratories might do the screening illegally, or affluent parents might take an overseas trip and come back pregnant with a designer baby. So legislation can’t entirely solve the problem even if we do decide that non-interference with sexual orientation is the best policy.

In conclusion, homosexuality has always been controversial. Modern attitudes see it as a natural trait, fixed before birth, and biological studies have revealed a definite genetic influence. While the research is not final, it seems that the sexual orientation of a child could conceivably be influenced by the selection of alleles by parents desiring a designer baby, or by selection of embryos during IVF by pre-implantation genetic diagnosis. If this is allowed, and widespread selection for heterosexuality occurs, homosexuals could find themselves a dwindling population. When genetic testing or deliberate allele selection becomes commonplace, this choice may be a dilemma for many couples.

References

• “What causes Sexual Orientation?“
• “The Biological Basis of Homosexuality“
• Hamer, D et al.  ”A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation”.  Science 261 (16 July 1993): pp 321-327.
• Egan, Greg. Cocoon (1994), in collection Luminous. (1998)  Millenium, London.
• Weiss, Rick.  ”Building a child with help from the gene genie.” Guardian Weekly, 12-18 July 2001.

Posted by Luke H on Friday, March 6th, 2009 at 11:36 pm.