weexx023: November 2011 Archives

Our psychology textbook puts a lot on emphasis on the fact that shared environment does not factor into a person's personality. Twin studies and adoption studies have been performed and identical twins are likely to share many of their personality traits and adopted children adopt the personality traits of their biological parents, even though they may never have had contact with them. Genetics seems to be the key driving force of how a person acts, thinks, and behaves.

New evidence in the field of neuropsychology has recently emerged that supports the hypothesis that a person's traits are determined by his or her genes.

Researchers have discovered an oxytocin receptor gene (OXTR) that is linked to social traits. Oxytocin is a hormone known by some as the "love" or "cuddle" hormone because it has a role in birth and bonding between mother and child. There are two behaviour-linked alleles of the gene- G and A.

According to the research, people with both copies of the G allele tend to be more social, outgoing, and more interpersonally inclined than those who have only one G allele or two A alleles. People homozygous for G allele are also at lower risk of mental disorders such as autism or schizophrenia. I infer that the G variant of the biological receptor allows better binding of the hormone to the active site of the receptor, leading to the positive, prosocial attitudes displayed by people.

People with GG would probably score higher in the extraversion area of the Big Five, and score lower in Neuroticism. Researchers said that people could instantly detect the genotype by a first impression of the person based on how the person acts in front of another. I would classify myself as a GA, and my best friend as an AA, whereas many of my coworkers would be GGs.

Since this study is new, more research on the gene/protein product must be done in order to confirm the validity of their hypothesis. Little is known about how these differences manifest behaviorally and whether they actually are readily detectable by outside observers.

http://www.bbc.co.uk/news/health-15693508

Sexual orientation is a polarizing and controversial topic of discussion in American society. Sadly, there is not much concordance between people about the origins of one's sexuality: many still believe that homosexuality is a choice, whereas modern science and Lady Gaga give evidence of people being born this way. It has entered the sphere of social politics, where perceptions of homosexuality have been clouded by heteronormative personal convictions and outdated religious dogma. It is my personal opinion that religion impedes the progress of humanity, so I will focus only on the biology of sexual orientation.

Many hypotheses exist for how sexual orientation is gained. In our textbook, it gives birth order, exposure to hormones/pheromones in the womb, early upbringing, and temperament as possible factors in determining it.

One hypothesis I found particularly interesting was that homosexuality was caused by a pathogen. As a microbiology major, I found the 'gay germ hypothesis' interesting. Gregory Cochran and Paul Ewald argued that evolution would strongly select against homosexuals, who have lower fitness (i.e. reduced chance of reproducing and passing down genes). This would make sense. In my biology class, however, we learned of kin selection- in this case, fitness of the homosexual's family increases because it devotes time to caring for its relatives' young, allowing their similar genes greater chance to be passed down.

Furthermore, they argued that higher prevalence of homosexuality in dense, urban areas suggested an infectious agent at work. However, you can't infer causation from that correlation- there might be another reason why there are more homosexuals in big cities such as bigger cities being more accepting and/or increased proportion because of a higher population.

The gay germ theory has largely been rejected by the scientific community because of lack of peer review and replicability. The American Philosophical Association said "there is ultimately very little to be said in favour of these contentions" that liken homosexuality to a disease that needs to be treated.

Sources:
An Evolutionary Look at Homosexuality by Gregory Cochran: http://home.planet.nl/~gkorthof/backup/An_Evolutionary_Look_at_Human_Homosexuality.htm
Crain, C. "Did a Germ Make You Gay?" in Out Magazine, August 1999.

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