Gender Identity: Nature vs. Nurture?

It has long been believed by the scientific community that the gender identity of a child was determined by the child’s upbringing, surrounding environment, and the way the child was treated during growth. This idea was only enforced more in the 1960’s when Dr. John Money published his John/Joan case, claiming that a child’s gender was constructed through nurturing, not nature.

The John/Joan case was an experiment that occurred after two twin boys, two months old, were sent in for a routine circumcision, but after a mechanical malfunction, one of the boy’s external genitalia was extremely damaged. The boy’s parents, counseled by Dr. Money, were encouraged and assured that if they surgically made their son appear feminine, with the help of administering hormones and their nurturing, they could raise the child successfully as a girl. While Dr. Money published this experiment as a great success, years later, a man named David Reimer stepped forward and identified himself as the object of the John/Joan case. Apparently, the John/Joan case that was published was riddled with observer bias and skewed results, and in reality, David was a troubled, depressed, sometimes suicidal girl growing up and immediately reassumed his male identity as soon as his parents told him the truth of his birth at age 14, but eventually committed suicide in his late 30’s in relation to the trauma and emotional distress incurred during his childhood.


Brenda Reimer growing up


David Reimer after reassuming his male identity

This begs the question, is gender identity nature and innate or is it, as Dr. Money would have led us to believe, entirely based on cultural and nurturing factors?

Research at the Johns Hopkins Children Center has shown that gender identity is almost entirely based on nature and is almost exclusively predetermined before the birth of the baby. Two studies conducted by William Reiner, a child and adolescent psychiatrist and urologist, have confirmed that the amount of exposure to male hormones and androgens in utero almost exclusively decides whether the child identifies as masculine or feminine.

In the first study, Reiner followed 14 children whose testicles and male hormone levels were completely normal at birth, but who were born without a penis — 12 of the children were surgically reconstructed to appear female. Today, all 12 of the children raised as females are strongly male a-typical in their behaviors, attitudes, friends and play and 6 of the 12 have already reassumed their male gender identities at the ages of 5, 6, 7, 8, 9, 11, and 12 respectively. The 2 children who did not undergo sex reassignment surgeries as infants developed far more normally and more similarly to their normal male peers and were much more psychologically well adjusted that the sex-reassigned children.

In the second study, Reiner followed 12 genetically male children who were born with a similar defect, in that they lacked a penis at birth. All of these children underwent a sex reassignment surgery to appear female in infancy. Since then, 8 of the 12 have reassigned themselves back to a male identity. Of the the 4 who remain female, 3 of the sets of parents plan to tell their child about their genetic sex at birth “soon” and all 3 sets of parents expect that their children will switch back to a masculine identity after learning about their birth sex.

Reiner comments on the results of the studies stating, “These studies suggest that male gender identity is directly related to normal male patterns of male hormone exposure in utero. These children demonstrate that normal male gender identity can develop not only in the absence of the penis, but even after the removal of testicles or castration at birth, and unequivocal rearing as female. Rather than the environment forming these children’s gender identity, their identity and gender role seem to have developed despite a total environment telling them they were female.” These and consequent other studies have caused the scientific community to reevaluate their belief that gender identity is constructed through “nurture”. Most scientists now believe that gender identity is something that is predetermined by a biological aspect and cannot be chosen for a child.

This new outlook has called for the reevaluation of sex reassignment surgeries on infants and parents who are considering one for their child are urged with extreme caution to consider letting their child decide on their own at a later age. Reiner believes, “These studies indicate that with time and age, children may well know what their gender is, regardless of any and all information and child-rearing to the contrary. They seem to be quite capable of telling us who they are.”

Facial Symmetry and Attractiveness

One of the leading aspects used to measure conventional attractiveness scientifically is facial symmetry.  Typically, this is measured by manipulating an original photo of a person (we are all at least a little asymmetric, no person is perfectly symmetrical) into a perfectly symmetric version of their face. This manipulated, symmetric image is then presented to test subject along with the original photo. Subjects are then asked to indicate which face is more attractive, usually indicating the symmetrical version. (These findings have been replicated in multiple studies.) Though these results indicate that people prefer and perceive the more symmetric faces as attractive, there has been considerable debate about why this is.

There have been two theories of substance proposed by researchers to explain the preference for symmetrical faces:

The Evolutionary Advantage theory proposed that symmetrical faces are perceived as more attractive because the symmetry indicates good health in an individual. Everyone’s genes are designed to develop a face perfectly symmetrical, but as we grow, develop, and then age, disease, infections, and parasites cause imperfection in our appearance (asymmetry). Thus, those that have less asymmetry and imperfections, are perceived as having better and stronger immune systems to withstand the infections and parasites that occur naturally. So, symmetry is a good indicator of a person having good genes to pass on their offspring. Under the Evolutionary Advantage view of symmetric preferences, we have evolved to prefer symmetry and perceive it as attractive because over human history we have consistently and constantly preferred healthier individuals for mates. In sum, the Evolutionary Advantage view suggests that attraction to symmetric individuals reflects an attraction to healthy individuals who would be good mates.

The second theory to explain the preference for facial symmetry is Perceptual Bias.  This theory suggests that the human visual system may be “hard wired” in a way that makes it much easier to process symmetrical stimuli than asymmetrical stimuli. If this is true, the ease of processing symmetrical stimuli would cause us to naturally prefer them to asymmetrical stimuli.  Under this view, preferences for symmetrical faces would be no different than for any other object. So according to this, as well as preferring symmetrical faces, humans would also prefer more symmetrical objects of any kind. This has been supported as it has been found that people much prefer symmetrical pieces of abstract art and sculptures to asymmetrical ones.

Little and Jones (2003) did a study to investigate why people prefer symmetric faces to asymmetric ones, by testing and attempting to apply predictions from both the Evolutionary Advantage theory and Perceptual Bias. Previous studies found that the symmetric preference is stronger for attractiveness of opposite sex than same sex. Little and Jones found that the manipulated, symmetric faces were judged more attractive when shown the right way up, but not when the faces were inverted. These findings suggest that symmetry is more important in mate choice stimuli than in other stimuli, supporting the Evolutionary Advantage theory and presenting multiple difficulties for the Perception Bias theory (if symmetry of any kind was preferred then the more symmetrical face would have been indicated as more attractive both the right way up AND when inverted).

real-portrait-left-side-symmetrical-right-side-symmetrical-1 real-portrait-left-side-symmetrical-right-side-symmetrical


If anyone is interested in learning more, you can benefit from taking a class or just researching Penn State’s very own Dr. Mark Shriver, a geneticist, who conducts research in Brazil on facial symmetry. Though ongoing, Shriver’s research has measured thousands of Brazilian (and other ethnicities) faces in facial symmetry, judging their scientific attractiveness and therefore contributing the most evidence towards the idea that mixed race people are more attractive — in this case attraction is not subjective, it is purely measure with symmetry. Shriver teaches many higher level ANTH classes, but if anyone is interested, I suggest starting with ANTH 021 – Biological Anthropology.

Selection for Homosexuality

Let me start this post off with stating that this is completely a factual and empirical post and that it has nothing to do with my personal views on homosexuality. Also, this is dealing with the genetic causes of homosexuality, which is only one of the facets in the ontogeny of sexual orientation in an individual. There are countless other factors and causes outside of genetics, but they are not relevant here.

That being said, scientists have been stumped for years because from an evolutionary perspective, homosexuality shouldn’t exist. Every species is governed by the evolutionary force of natural selection. Selection chooses between variations in a population to select traits that will most help an individual to survive it’s environment and improve its reproductive fitness. (Side note for those unfamiliar with biology, reproductive fitness is how successful an individual is in reproducing and passing their genes on to the next generation.) Keeping all of this in mind and continuing with this logic, homosexuality is an obvious disadvantage to individuals. By being homosexual, individuals prefer their own sex, with who it is impossible to mate with, effectively decreasing their reproductive fitness to a nonexistent level. Normally, when a trait is this harmful to an individual’s reproduction fitness, evolution will select against it and eventually (but still rather quickly), it will disappear from the population entirely.

Despite this logical argument, homosexuality persists in contemporary society, stumping scientists and leading to several explanations as to its continuing existence:

In 1959, ecologist G. Evelyn Hutchinson proposed that gay genes were still persistent in society due to a heterozygous advantage. This hypothesis states that there are different alleles for the gay gene – individuals who are homozygous for this gay gene are more likely to become homosexual (in combination with other factors) and therefore suffer a reduced fitness, while individuals who receive two different alleles for the gay genes and are heterozygous, are heterosexual and experience an average higher fitness than normal. This gives individuals who are heterozygous for the gay gene an advantage over those individuals who don’t possess the gay gene, thus maintaining it in the population.

In 1975, Edward O. Wilson suggested a different hypothesis. This time, he proposed that homosexuality still persisted because it encouraged altruism and kin selection. Both of these mechanisms can be found in other species throughout the animal kingdom. The simplest explanation is that rather than invest in their own reproductive fitness, individuals abandon mating efforts to help and assist in raising the offspring of close kin, like parents or siblings, who share a large portion of the individual’s genetic make-up, allowing them to pass on their genes without actually producing any offspring. However, it appears that homosexuals do not have an overwhelming inclination to contribute to the reproductive success of their relatives compared to others enough to outweigh the costs to their own fitness. So while this hypothesis could help explain the continuity of homosexual orientation in contemporary society, it could not stand alone and would have to be in combination with other factors.

In 1991, it was suggested by two scientists, J. Michael Bailey and Richard C. Pillard, that homosexuality in both men and women was a polygenic trait, meaning that it wasn’t controlled at one, single genetic locus. If this is the case, then it is possible that natural selection wasn’t favoring homosexuality, per se, but rather favored the genes for testosterone production or some other adaptive trait that is also associated with some of the same genetic alleles. If a certain combination of these alleles at multiple loci can help contribute to homosexuality than it would continue to persist, despite its detrimental effects to a individual’s fitness.

Lastly, a hypothesis of antagonistic pleiotropy has been recently proposed and revised in both 1994 and 2004. This refers to that though a gay gene could decrease the fitness of homosexuals, it could increase the fitness of their closest, non-gay, male relatives (brothers, fathers, uncles etc.) An alternative to this, is that it increases the fitness of sisters and other female relatives of homosexuals. This alternative is especially probably as research shows that the gay gene most likely resides on the X chromosome, which females posses two copies of, unlike their male counterparts. In a study at the University of Padova in Italy in 2004, researchers found elevated reproductive success in the maternal relatives of homosexual men (both male and female) — significantly higher reproductive success of the mothers, maternal aunts, and non-gay maternal uncles of homosexual men, supporting the antagonistic pleiotropy hypothesis.


Puts, David A. “The Ontogeny and Evolution of Homosexuality.” The Evolution of Human Sexuality: An Anthropological Perspective. Second ed. Dubuque,Iowa: Kendall/Hunt, 2009. 278-94. Print.

Third Genders: New Concept? Or Old?

In nearly all of human history and, in particular, human culture, we have recognized and integrated at least two genders. For most societies, this means labeling two sexes (male/female) and two genders (man/woman) with the ideas of transsexualism and homosexuality being their own separate sect as novel and unprecedented, however cases of a “third gender” are well documented in multiple societies.

There are an overwhelming amount of examples of another or “third gender” in cultures in the past:

  1. In indigenous Hawaii, before its colonization, there was a long standing multiple gender tradition, where the mahu could be a male or female biologically, but decide to inhabit a gender role either opposite theirs, somewhere in between the traditional sex roles, or even both masculine and feminine roles. Instead of being written off as outcasts, as persons of atypical gender identities often are today, these mahu were revered in their social roles as sacred educators of ancient traditions
  2. In ancient Incan culture, the Incas worshipped a “dual gendered god” known as chuqui chinchay, who could only be attended and honored by third gender shamans or servants who wore androgynous clothing as “a visible sign of a third space that negotiated between the masculine and the feminine, the present and the past, the living and the dead.”
  3. Among the Sakalavas of Madagascar, there is a third gender group reserved especially for little boys thought to have a feminine appearance and personality. These boys, rather than labeled as “gay men” after maturing and experiencing the upbringing of a male, are instead raised by their parents as girls from a young age.

Though many of these societies may refer to transsexuals or homosexuals as a third or separate gender, most of the time, these extra genders represent individuals who identify neither as men nor women. To most of these cultures, this means that the third gender symbolizes the intermediate condition between the genders or a state of being both. (This is often described as the “spirit of a man in a woman’s body” and vice versa.) In layman’s terms, this means that individuals included in this third gender either have no gender affiliation, have the ability to cross or swap between genders, or are a gender category all together independent of the traditional male and female roles.

It doesn’t always stop at third. Third genders are widely accepted as being understood as an “other” gender, but fourth, fifth, and sixth genders have been documented by anthropologists as well.

In contemporary societies, people have started to draw a line between sex (biological and anatomical nature) and gender (social and psychological nature). Many modern societies continue to be conservative with their idea of gender and only recognize a two-gender system, which they, ethnocentrically, believe to be the social norm. This is known as “heteronormativity”:

  •  female genitalia = female identity = feminine behavior = desire male partner
  •  male genitalia = male identity = masculine behavior = desire female partner

Third genders are still documented in contemporary society today. The most well known of these cases are recorded in the Indian subcontinent in the roles of the “hijras”. Hijras are born intersex or male, but dress in feminine clothing, retaining a gender that is neither male nor female. They are often misrepresented as eunuchs to the Western world, when very few hijras are castrated. British photographer Dayanita Singh wrote about her friendship with an Indian hijra where she reported, “When I once asked her if she would like to go to Singapore for a sex change operation, she told me, ‘You really do not understand. I am the third sex, not a man trying to be a woman. It is your society’s problem that you only recognise two sexes.'” Hijras are widely recognized and accepted in Indian culture and since 2005, there has even been a third gender option to choose from on Indian passport applications.

Many modern Western societies have no direct correlation to the “dual gendered”, masculine and feminine third gender group, (often referred to as “two-spirited” in Navajo culture) or even an equivalent for communities that have very loose and fluid conceptions of sex, sexuality, and gender. Gender expression varies greatly from culture to culture globally and you can go online to PBS’s website to take a worldwide tour of other cultures to explore gender diversity.


Growing Older Sooner

One of the alarming trends in the US, as well as other foreign nations around the globe, is that girls are maturing earlier. In contemporary times, it is common for young girls to start the beginning stages of puberty (hair growth, breast development, etc.) at 7 or 8 years old, a record breaking age compared to past centuries. While the menarche (first period) still does not show itself till about twelve years of age, this is still an unprecedented early age when looking at the trend of first menstruation over the 1800’s and the 1900’s.

First noticing this trend over 140 years ago, researchers began documenting the age of the first menstruation. In 1860, the average age of menarche was occurring at 16.6 years old, showing a steep decline in the following decades, marking it as 14.6 years in 1920 and 13.2 years in 1950. While this trend seems to finally have leveled off since the 80’s where the last recorded and most accurate age is 12.5 years old, the rate at which the first stages of puberty is observed is still rapidly declining.

Boys, like girls, are also seeing the emergence of puberty (facial hair, growth spurts, etc) at younger and younger ages, but the trend toward full blown puberty at an earlier age is not as rapid or as pronounced as it is the female sex.

Another epidemic affecting more and more young girls, is the problem of precocious puberty – or premature puberty. Scientifically, this is defined by breast development accompanied by a growth spurt in girls younger than the age of 8. Due to the decreasing trend in the age of girls at the start of puberty, there is a lot of debate over what age is actually too young (considering the norm) and should be defined as “precocious”.

There is also argument over what actually constitutes the onset of puberty. Dr. Lawrence Silverman, a pediatric endocrinologist at Goryeb Children’s Hospital in Morristown, New Jersey argues that sometimes precocious puberty is wrongly diagnosed, stating “The appearance of acne and pubic hair is common even in infants and toddlers. It goes away. We need to be careful about how we identify the true onset of puberty.” In most cases of true precocious puberty, the body will eventually correct itself, causing the process to slow down and stall, but not before causing menstruation in the premature, often emotionally unprepared girl.

Despite the overall decline in age of the onset of puberty, the data does differ vastly when considering variables like race. In the US, for example, African-American and Hispanic girls tend to reach puberty earlier than their white counterparts by 1-1.5 years. The mean age of breast development in African-American girls in the US is 8.9 years old compared to the much older 10.5 years that is the mean age for breast development in Caucasian girls. While the cause of this is unclear, there are many, interacting factors affecting the situation.

While everything from economic reasons to climatic change to genes has been cited as part of the cause in the decline of age at the onset of puberty, none of these can explain the overall reduction, rather than just individual cases.

One of the most widely held beliefs is that improved nutrition in modern times has caused bigger and heavier children than in the past, allowing for normal growth. Another probable cause and one with the most evidentiary proof is the rising epidemic of obesity globally. At the annual conference of the American Academy of Pediatrics in Orlando, Florida, in 2001, pediatric endocrinologist Dr. Paul Kaplowitz presented a study he conducted that included girls from the ages of 6 to 9 and helped discover a link between body fat and the timing of puberty.

Beyond loosely linked evidence and slight correlations, the scientific community is still perplexed and unable to explain the reduction of age in the onset of puberty and the rapid increase of precocious puberty, leaving it a hot topic for future studies.


Discovering human sexuality through the years.

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