Emerging Scholars Blog

InterVarsity's Emerging Scholars Network

homosexuality

Science Corner: The Skinny on Genes

photo of paired columns with banding patterns reminiscent of chromosomes
I assume that this is some kind of art installation and the resemblance to chromosomes is intentional; whatever it is, I thought it was cool. (Photo by bitmask )

Biology is not fully reducible to genetics, and behavior is not fully reducible to biology. I’ve found myself using that adage more often in conversation, so I thought perhaps it would be helpful to mention and unpack here. As far as I know, that particular phrasing is mine, but the sentiment I believe is fairly representative of what biologists think. While there may be a popular expectation finding genes for every personality trait, the reality is that genes can only have so much influence. That should be apparent even from the raw numbers. We have roughly 25,000 genes and 100 trillion neural connections; so few genes cannot possibly fully specify how our brains are wired, especially considering everything else those genes also have to do. Even when genes get a label like the “warrior gene” the most we can about it is that it is associated with a higher tendency toward certain behaviors, rather than being fully deterministic.
[Read more…] about Science Corner: The Skinny on Genes

Science in Review — September 2013

Painting of Satan offering to turn a stone to bread to feed Jesus
Would Jesus have been tempted if his physical body didn’t experience hunger? The Temptation of Christ in the Wilderness by Juan de Flandes [Public domain]

This is the fifth and final post in a series on the topic of biology and sexual orientation.

I set out to write this series primarily as a forcing function to update my own understanding of the evidence for biological mediation of sexual orientation. After reviewing studies on heritability and the biological pathways, I have satisfied myself that there is a biological dimension to orientation. So now I suppose the question becomes: what does that mean?

For starters, let’s consider what that means with respect to homosexuality and sin. The best answer I can come up with is: not much. Ultimately, matters of sin and righteousness are theological or perhaps philosophical questions, not scientific ones. I’ve hedged in the past on whether I can call myself a scientist, but I know I am not a theologian or a philosopher. The most I would be prepared to say is that biological mediation does not rule out the potential of it being a sin.

[Read more…] about Science in Review — September 2013

Science in Review — August 2013

Brain
Can the physical structure of your brain really tell something about your sexual orientation? From “The Anatomy of the Brain”; public domain

This is the fourth post in an ongoing series on the topic of biology and sexual orientation.

Last month we talked about the evidence for the heritability of sexual orientation. The upshot of that seems to be that it is partially correlated with certain genes, or with inheritance in general (as estimated by twin studies), but that genetics only tell part of the story. There is still plenty of room for contributions from other factors post-conception. However, that doesn’t mean that there aren’t other biological determinants. So this month we’ll take a look at what is know about the biological mechanisms of sexual orientation.

Our general intuition is that orientation and attraction are functions of our brain and/or our mind. (Recall from the first post in this series that many scientists in these fields think of the brain and the mind as effectively the same thing, while others consider them separate.) So that is a natural place to look. We don’t have great tools for examining the mind (to the extent that it is separate) but we can look at the brain; that investigation began with this study by Le Vay from 1991. Brains of people of different orientations and genders have been examined, and differences have been observed between the brains of heterosexual men and homosexual men, although the exact details of the differences differ. For example, this 2001 study by Byne et al only partially reproduced Le Vay’s findings. [Read more…] about Science in Review — August 2013

Science in Review — July 2013

Zygote
Was your sexual orientation decided while you still looked like this? From “Gray’s Anatomy”; public domain

This is the third post in an ongoing series on the topic of biology and sexual orientation.

Having dealt with what I felt were some necessary preliminaries, we now turn our attentions to the main questions about the biological mediation of sexual orientation, starting with issues of genetics and heritability.

To what extent is sexual orientation passed from parent to child, and how much of that inheritance can be attributed to genes?

Since we are restricting ourselves to human studies, that limits the kinds of genetic research that can be done. In those cases, scientists rely on what they call natural experiments — in other words, observing what occurs naturally rather than deliberately establishing test conditions of interest. One of the most popular natural experiments in genetics is the birth of identical (monozygotic – from the same fertilized egg) twins or fraternal (dizygotic – from different fertilized eggs). Since twins tend to be raised in environments as similar as we can muster, evidence of greater similarity in identical twins compared to fraternal twins is generally attributed to their genetic similarity.

[Read more…] about Science in Review — July 2013

Science in Review — June 2013

Adult penguin with two chicks
Pairs of male penguins have been seen raising chicks. Is this homosexual behavior? Does it tell us anything about human behavior? (Public domain)

This is the second post in an ongoing series on the topic of biology and sexual orientation.

Last month, I talked about how the longstanding philosophical questions of the mind-body problem might inform or bias our understanding of how biology mediates sexuality. There was some question as to whether having a monist or dualist perspective is as significant to the topic as I theorized, but I still think it is relevant. In fact, I wonder whether the assumptions that stem from those perspectives are so fundamental to our thinking that they seem obvious and hard to imagine being any other way.

Nevertheless, setting aside the mind-body problem, the next assumption I found myself thinking about was the connection between animal behavior and human behavior. A lot of research on the biology of sexuality focuses on animal studies, either as a way to develop hypotheses to test in humans, or as an indirect way of understanding human biology and human behavior. This is for all of the usual reasons why animals are studied — lack of privacy concerns, (relative) ease of creating controlled conditions, shorter generation times (especially helpful for genetic studies), etc. Specific to this domain, there is also the ability to directly observe the behaviors of interest, rather than relying on surveys or other self-reported measures of behavior. But depending on one’s understanding of the relationships between humans and animals, this evidence will be more or less convincing.

[Read more…] about Science in Review — June 2013