Two New Studies point towards complicated nature / nurture mix

Two new studies on the origins of sexual orientation have been released in the past few days. The first is a twin study for which the abstract is as follows:

There is still uncertainty about the relative importance of genes and environments on human sexual orientation. One reason is that previous studies employed self-selected, opportunistic, or small population-based samples. We used data from a truly population-based 2005–2006 survey of all adult twins (20–47 years) in Sweden to conduct the largest twin study of same-sex sexual behavior attempted so far. We performed biometric modeling with data on any and total number of lifetime same-sex sexual partners, respectively. The analyses were conducted separately by sex. Twin resemblance was moderate for the 3,826 studied monozygotic and dizygotic same-sex twin pairs. Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance, the shared environment .00, and the individual-specific environment .61–.66 of the variance. Corresponding estimates among women were .18–.19 for genetic factors, .16–.17 for shared environmental, and 64–.66 for unique environmental factors. Although wide confidence intervals suggest cautious interpretation, the results are consistent with moderate, primarily genetic, familial effects, and moderate to large effects of the nonshared environment (social and biological) on same-sex sexual behavior.

The press release that accompanied the paper drills down to the core issues involved:

"The results show, that familial and public attitudes might be less important for our sexual behaviour than previously suggested", says Associate Professor Niklas Långström, one of the involved researchers. "Instead, genetic factors and the individual’s unique biological and social environments play the biggest role. Studies like this are needed to improve our basic understanding of sexuality and to inform the public debate."

A second paper is a much smaller piece of research looking at brain structure variations:

Striking similarities between the brains of gay men and straight women have been discovered by neuroscientists, offering fresh evidence that sexual orientation is hardwired into our neural circuitry.

Scans reveal homosexual men and heterosexual women have symmetrical brains, with the right and left hemispheres almost exactly the same size. Conversely, lesbians and straight men have asymmetrical brains, with the right hemisphere significantly larger than the left.

Of course we’ve seen this before in the work of LeVay and others, and the sample is at the bottom end of the barely usable scale. That said, Warren Throckmorton has same very useful observations:

On the other hand, Savic and Lindstrom are not proposing that these differences cause the sexual orientation differences. Those familiar with Daryl Bem’s exotic becomes erotic theory will see how these brain differences could support his theory. It is plausible that these brain differences are involved in the gender atypical behavior so commonly and strongly associated with the development of adult homosexual orientation. Gender atypical behavior could be an associated feature of a same-sex orientation, a kind of sign of homosexual orientation or in the EBE account, gender atypical behavior and interest could predispose people to sexual regard the same sex as the other sex during pubescence.

Savic and Lindstrom propose three potential mechanisms for these differences. They note:

The mechanisms behind the present observations are unknown. In accordance with discussions about the sexual dimorphism of the brain, three factors have to be taken into account: environmental effects, genetics, and sex hormonal influences.

These are the usual suspects, genes, environment and hormones. Savic and Lindstrom dismiss genetic factors for reasons I cannot quite figure out. They say,

As to the genetic factors, the current view is that they may play a role in male homosexuality, but they seem to be insignificant for female homosexuality. Genetic factors, therefore, appear less probable as the major common denominator for all group differences observed here.

About environment, they observe that sex-based brain differences have been observed at birth and in children. However, cerebral maturation continues through puberty, especially in boys. Thus, social and environmental factors could play a role in how these differences or other differences not assessed here develop in individuals. They are not certain however and note:

However, to attribute such effects to the present results would require a detailed comprehension of how specific environmental factors relate to the four groups investigated, and how they affect various cerebral circuits. In the light of currently available information this can only be speculative.

In other words, we do not know what environmental factors could be influential on brain differentiation for male and female with sex typical and atypical brain structure and function. The authors are either unaware of Bem’s EBE theory or do not see it as relevant to their findings. Clearly, these wanted to rule out the role of sexual behavior and preference as being the driver for the differences between gays and straight that they found in their pheromone studies. Here they believe they have found clear neurological differences which in some manner relate to the differences in sexual preferences

All the recent research seems to be pushing us to the conclusion that sexual attraction is conditioned by a complicated interplay of nature and nurture which may be unique for each individual. While reparative therapy might work for some, for others it will have no effect. That’s why I favour an entirely spiritual approach to discipleship of those struggling with same-sex attraction, focussing on thw surrender to the sovereignty of God and a life of dedicated holiness, the openness to healing but also a dying to the "need to be straight". Such a path has served me and many others well and I believe it is in the direct line of classical christian spiritual direction.

8 Comments on “Two New Studies point towards complicated nature / nurture mix

  1. Peter said: ‘that’s why I favour an entirely spiritual approach to discipleship of those struggling with same-sex attraction, focussing on the surrender to the sovereignty of God and a life of dedicated holiness, the openness to healing but also a dying to the “need to be straight”.

    Cool – I agree with you Peter; I hope that is how I live my life, surrender to God, holiness of living, a willingness to embrace God’s healing, and a constant dying to the ‘need to be straight’ as understood by the so called norms of our society.  Of course, I do this as an openly gay Christian.

  2. On that, we will have to disagree, but the measure of agreement is significant, and in that we should rejoice!

    Pondering Sunday’s Gospel reading, not easy stuff – sounds like the Church of England though, all about division.  Do you follow the authorised lectionary in your parish?  If not, take a look at Matthew 10:24-39.

  3. I find your concept of dying to obsession with heterosexuality quite refreshing and i think it is certainly classical Christian discipline.

    I wonder at your comment about holiness. Holiness is a state of being marked by separation from the norm. God is Holy because God is not normal.  So with 98% of people heterosexual, there’s nothing holy about being straight. The only holy sexuality I can think of is celibacy. And I refer to heterosexuals as well. While the Church has forgotten the real meaning of holiness (it is not synonymous with righteousness) we lose an important part of our religion.

  4. I think, given the symbolism that Ephesian 5 indicates that married sex has, we can say that marriage can be and is designed to be, holy (and therefore how any other form of sex is unholy).

  5. With regard to the matter of holiness, I would agree entirely with the Working Group of Catholic Gay Pastors of the Netherlands when they write:

    Gay and lesbian people, too, have received the vocation to holiness. Sexual abstinence is not per se, and for most simply not, the way there. Nor does the way lie for anyone in the denial of one’s sexual desire.
    Called to Blessing: A Pastoral Letter on Faith and Homosexuality (1992)

    Disputes over the symbolism employed in Ephesians 5 and over its present-day implications and applicability are scarcely relevant here. If gay relationships don’t fit the symbolism of Ephesians 5, then so what? The author is talking about heterosexual marriages, and a gay relationship isn’t a heterosexual marriage: there is no a priori reason why a gay relationship should need to symbolize everything that a straight relationship does, nor is there any reason to be dismayed if it doesn’t or can’t.
    The author of Ephesians clearly didn’t have gay relationships in mind when he wrote, and I go along with Fr John Wijngaards when he said that it is wrong to ascribe statements or intentions to a biblical author which lie outside his scope, and that a text of Scripture cannot say more than its human author intended to say. It is for this reason that, I must admit, I have to regard the recent use of a “gay-adapted” version of the Anglican marriage service as ill-judged and inappropriate. As far as I’m concerned, a gay relationship is perfectly good and fine precisely for what it is; an attempt to “validate” it by presenting it as a caricature of a straight relationship is neither necessary nor desirable.
    It was, I think, Fr Bernard Lynch who postulated that part of the Godhead must be gay. If he’s right, then no doubt a gay relationship can mirror or symbolize some other precious aspect of Christ and his relationship with humanity.
    (By the way did Paul himself actually write the Epistle to the Ephesians? There is apparently a considerable body of opinion among modern biblical scholars which holds that he didn’t – that Ephesians is deuteropauline. See e.g. UDO SCHNELLE, The History and Theology of the New Testament Writings (1998), pp. 300-3003. However that’s a matter for the scholars to sort out.)

  6. Re the first study
    Those confidence intervals were not only wide, but included zero except in the variance explained by the unique environment. So I had a closer look. The first thing that became obvious is that female twin pairs comprised approximately 2/3 of the final sample (the final sample consisted of those mono or dizygotic twin pairs who both responded to the questions and thus were included in the analysis). For me it follows that the analysis will have more predictive power for the women twin population because their sample is much bigger. A larger sample predicts a smaller confidence interval (CI) and if we look at the data, we find that CIs are indeed consistently smaller in the female sample.

    Overall, though, the sample sizes were large for both sexes. Then why these massive CIs? e.g. in men the heritability estimates at 95% confidence fall between 0 and 59% (this means that 95 times out of a 100 the sample percentages will fall within the confidence interval, in this case between 0 and 59) for “any lifetime partners” and just slightly less (0-53%) for “total number of lifetime partners”. Contrast that with CIs obtained for the nonshared or unique environmental factors: for males it is between 41-85% and 47-87% respectively. I might be totally wrong, but I think the evidence for unique environment effects is more convincing than the evidence for heritability.

  7. @Peter
    Eph 5 says nothing about marriage being holy – that is your own deduction. It says the Church-Bride should be holy. Ie, not the norm or set apart. I’m not sure, but I think you’re equating holiness with being blameless (which that would make that very verse silly and redundant if that were the biblical understanding of holiness).

    A marriage can be holy, I suppose, if it is set apart from other marriages in a positive way. If it’s faithful, honest, committed, honoring, etc. I see no reason a gay marriage can’t be holy. Well, unless you argue a gay union can’t be marriage by definition, but then we’re just arguing over words. In any case, a gay union can be holy.

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