By Maria Nieto
Maria Nieto, Ph.D., a professor of biology in the Department of Biological Sciences at California State University, East Bay, filed an amicus brief on February 28, 2013, in support of the parties opposing Proposition 8 before the U.S. Supreme Court. The 2008 California ballot measure known as Proposition 8 specifies that, “Only marriage between a man and a woman is valid or recognized in California.” Dr. Nieto received her Ph.D. from the University of California, Berkeley and has taught for nearly 25 years at CSU East Bay. She was featured recently in “Somos en escrito” as author of a mystery novel, her first fiction work, titled Pig Behind the Bear.
As a biologist I have found the arguments against same-sex marriage misguided. Not because of the evidence, albeit inconclusive, which hints at same-sex attraction as being based, at least in part, on biological roots, but because the same reasons used to ban same-sex marriage could also be applied to what appear to be opposite-sex (heterosexual) marriages. It may be shocking to hear that the sex and gender of every individual in our population does not fit into a nicely defined “box” that can be labeled male or female/man or woman.
The idea that all individuals fit into a “box” of either one type or another works well with laws that limit marriage only to a union between a man and a woman. However, observations that substantiate tremendous diversity in sex and gender within our population pose a biological conundrum: How should we define the terms man and woman, and are they the same as male and female?
Male and female are biological designations used to define one’s sex. Generally the two sexes are distinguished by whether they produce sperm or eggs. Of course for one to be able to produce sperm or eggs, and ensure that sperm and eggs are able to meet up, as a first step toward ultimately producing a baby, each sex needs to possess functioning internal and external reproductive tissues and organs.
Even though one’s sex is defined by the ability to produce sperm or eggs, many of us would have a hard time stripping an individual of their sexual distinction if they were for some reason unable to produce viable and/or functioning sperm or eggs. Therefore, we have accepted individuals as being male or female based, in large part, on how they “look” physically. For example, a female would possess a vagina in addition to other female associated “parts”, and a male would possess minimally a penis.
The development of male and female parts is determined by the genetic information contained within the chromosomes we possess, and two of these are referred to as sex chromosomes. The sex chromosomes possessed by a typical male are designated as X and Y, and for a typical female XX. Although other, non-sex chromosomes that are part of the greater chromosome collection definitely play a role in male and female development, the presence or absence of the Y chromosome is critical in cueing the early embryo to develop male or female parts.
It might seem reasonable to assume that all males would possess XY chromosomes and associated male physical parts such as a penis, and females would possess XX chromosomes and associated female physical parts such as a vagina, but this would be an incorrect assumption. It is estimated that at least 1 in every 2000 individuals in the population do not fit this pattern, and for the United States this translates into approximately 150,000 people or the population of Dayton, Ohio or Pasadena, California.
Although there are many examples of how a variation in chromosome composition and concordant anatomy can occur, one example is called androgen insensitivity syndrome or AIS. Individuals with AIS are represented in the population at a frequency of 1/12,000. In one form of AIS, individuals look like females externally; they lack a penis and possess breasts. Minimally however, these individuals possess the male XY chromosomes and are born with testicles that can remain in the abdominal cavity, hidden from external view. This variance occurs because the developing embryo fails to make functioning receptors that are capable of binding to an important chemical cue called testosterone, which is needed to spur many biological events, namely the development of male specific reproductive organs and tissues such as a penis. Without receptors the hormone has no effect.
Thus, the existence of AIS in the population begets an interesting question—are individuals with AIS male or female? If we base the determination on chromosomes alone, then the answer would be male. And if these individuals are male, and married to XY, penis-bearing males, can their marriages truly be qualified as heterosexual? Some would argue that aside from chromosomes other factors must be taken into account in determining one’s sex.
After all, individuals with AIS may never know they are chromosomally male unless they seek medical attention regarding painful intercourse that can occur due to a shallow vagina, or their inability to menstruate or get pregnant due to the absence of a uterus, fallopian tubes, and ovaries.
Should one’s sex then be based on how they “look” externally? There are cases of AIS called Partial AIS (PAIS), where the individual’s testosterone receptors slightly work, allowing for the development of a penis. In this situation does the answer change? Does the individual’s possession of a penis and XY chromosomes now make them a male, even though in every other physical regard they could pass in our society as female? And if so, would their marriage to a typical, non-AIS penis-bearing male be valid?
Some might argue that depends on the sex the person was assigned at birth, and consequently the sex listed on their identification card. However, what if a sex assignment is made at birth that ultimately turns out not to match the person’s gender?
Although gender is commonly used interchangeably with sex, gender is determined based on cultural and social mores and refers to definitions associated with man and woman or masculine and feminine. For most individuals, one’s sex and gender match. For example, males would self-identify as men, and females would self-identify as women.
However, in the case of PAIS, sexual assignment cannot be strictly defined, or might be inaccurately assigned so as to not match gender. What is the marital fate of a PAIS individual who has been assigned the sex of female, yet self identifies as a man, and is sexually attracted to females? Who will this person be allowed to legally marry?
In most of the 50 states that make up our country’s union, the identification cards presented to the clerk by the two persons desiring a nuptial must state male on one and female on the other. In other words, the sex of the two “pre-weds” must be opposite. Matthew Staver, founder of the Liberty Counsel, an organization that opposes same-sex marriage, says, “What you’re born with is what you are”. In essence, marriage legitimacy should be based on birth sex.
In 2004 he argued and won a case that nullified a marriage between a post-operative female to male transsexual and a typical, biological female. He won because the court ruled that both individuals shared the same sex, each born female and in possession of XX chromosomes. To be consistent with his own tenet, Matthew Staver should be arguing against the legitimacy of thousands of “heterosexual” marriages that are in fact unions between individuals possessing the same chromosome composition.
Biological variation is common among all species and exists naturally. I do not believe we will want to establish a list of criteria to determine what defines a man and a woman, and as a consequence control who is fit to marry whom. There is no need to call into question the legitimacy of thousands of “heterosexual” marriages that are really same-sex unions. Instead, we can decide to embrace biological diversity.
| Image may be NSFW. Clik here to view.  |
| Maria Nieto |