Revisiting: Genotype-Environment Correlation

("Gene-Environment Interaction"; This is the name of the article that I got this picture from, but my post itself focuses on genotype-environment correlation.)

Previously, I wrote a post describing the concepts of genotype-environment correlation and genotype-environment interaction as well as their application(s) to the behavioral differences between introverts and extroverts.  However, after speaking with my mentor, I find that I may have glazed over some of the more important points to these concepts and/or misinterpreted their application(s).  Thus, I plan to revisit the concept of genotype-environment correlation in this post, and I will revisit the concept of genotype-environment interaction in next week's post.  In revisiting these concepts, I believe that I can provide more comprehensive and accurate explanations, which will not only allow my audience to better understand these topics and their application(s) to the behavioral differences between introverts and extroverts, but it will also provide me the chance to ensure that I have a firm grasp of these concepts as well.  For my post today, I will be using the textbook Behavioral Genetics, Sixth Edition, by Robert Plomin, John C. DeFries, Valerie S. Knopik, and Jenae M. Neiderhiser as my main source of information.

The driving idea behind the concept of genotype-environment correlation(s) is that "we create our experiences in part for genetic reasons."  In other words, the environments that individuals are subjected to and/or create, whether willingly or inadvertently, are partially products of the individual's genotype/genetic traits.  As previously discussed, the definition of a genotype is "the genetic constitution of an individual organism."  Thus, even by the name of the concept itself, one can reason that the genotype-environment correlation is a concept in which the environment that one lives in is a product of their behavioral tendencies, which are coded for in their genetic makeups.  In some instances, what may seem to be an environmental influence may simply be a reflection of genetic influence/identity.  Individuals may assume that being subjected to a certain environment affects a certain trait, but it may be the trait itself, coded for genetically, that leads to the individual being subjected to the environment.  Due to its nature, "genotype-environment correlation has been described as genetic control of exposure to the environment."

("Heredity")

A crucial point to note about genotype-environment correlation is the individual does not necessarily have to subject themselves to said environments willingly in order to display a correlation between their genetic tendencies and choice of environment.  Environment amplifies the behavioral differences between individuals in that the environments that they subsist in are a reflection of their genetic tendencies, and the fact that the individual is genetically suited for such environment further illustrates variance in behavior.  In order to organize the different ideas surrounding the central of concept of genotype-environment correlation, researches and scientists have designed three types of genotype-environment correlations for different situation to fall into:

1. Passive Type
"The passive type occurs when children passively inherit from their parents family environments that are correlated with their genetic propensities."  In simpler terms, because many of our traits are genetic, and because we inherit our genes from our parents, we share many of the same traits with our parents, whether we like it or not.  Although individuals may look physically different from their parents, their actions and behaviors will always exhibit some influence from their parents' genes.  As a child/adolescent, one's parents subject themselves to an environment that suits the parents' needs as well as the kid's/kids'.  In other words, parents actively create an environment of their liking at home that suits their genetic tendencies and normal behaviors.  Whereas the parent is actively creating this environment, however, the children are simply forced into the environment.  At the same time, because this environment is based on their parents' genetic tendencies, behaviors, and interests, and because individuals inherit many of their genetic tendencies, behaviors, and interests from their parents, they passively subsist in this environment as well.  Although this environment is likely not created with their "genetic propensities" in mind, this environment still accurately meets the individuals genetic tendencies.  As a result, one's demonstration of behavior and genetic propensities is amplified, as they are comfortable in an environment that suits their behavioral needs (at least for the most part).  In the previous post, I mentioned the textbook's example of a musically gifted child.  The musically gifted child has it in their genes to express musical talent, and they inherited this predisposition to musical talent from their parents.  Their parents, who thereby would also have to be musically gifted, would provide their children an environment conducive to the development of musical ability, as they themselves would feel best comfortable in such environment.  Because this environment suits the parents' behaviors, genetic tendencies, and interests, it will also suit the child's genes and predispositions, as they inherited their genes from their parents.  An individual could have musical ability, but if they are not subjected to a home environment that is conducive to music-making, they will not be given the opportunity to display this ability.  However, because in this situation the home environment is conducive to the development of music, the child's behavior(s) and predisposition to musical talent will stand out.  Likewise, the probability is that if you are an introvert/extrovert, your parents will likely demonstrate the same leanings as you.  Given that many/most traits are heritable, it is safe to assume that introversion/extroversion, the results of biological functions, are heritable by effect.  In passive type genotype-environment correlation, the child does not create the environment, but the parent does.  Obviously, introvert-type parents would conduct environments conducive to introverts (through rules, mannerisms, traditions, etc.) whereas extrovert-type parents would conduct environments conducive to extroverts.  By effect, as introvert-type children will likely be born to introvert-type parents and extrovert-type children will likely be born to extrovert-type parents, each child would usually be subjected to the environment conducive to their behaviors.  The child does not necessarily change in respect to introversion/extroversion because of their environment, but because of their environment and its accommodation to their genes, they feel more freely to express their innate behaviors, which are amplified.  Thus, even as children, introverts and extroverts will demonstrate their respective behaviors, coded for in their genes, because of the conductivity of their environment, created by their genomically equal parents.

2. Evocative Type
"The evocative, or reactive, type occurs when individuals on the basis of their genetic propensities, evoke reactions from other people on the basis of their genetic propensities."  Once again, in this situation, the individual does not intentionally create the environment for themselves.  Rather, based on the behaviors and predispositions that they express, individuals evoke a response from others, who react and adapt to create an environment "fitting" for that individual.  In other words, the individual does not actively seek out an environment conducive to their interests, talents, genes, etc., but they instead let it come to them.  In most instances, adults will recognize the genetic tendencies that a child or peer express and recommend them for some program/opportunity/activity that they believe will fit their makeup, or children and/or adults may simply recognize these expressed genetic tendencies, and, recognizing that these traits are similar to their own, they make friends with the individual.  In essence, the individual does not intentionally create the environment.  Other individuals, who recognize the individual's talents and behaviors, instead react and create the environment; in other words, the individual's genes, by effect, create the environment.  At this point, once again, the situation that the individual is placed in is again representative of their genetic tendencies and behaviors, without even looking into how the individual acts in such environment.  By studying how the individual subsists in such environment, however, their genetic tendencies, talents, and behaviors are amplified, putting more emphasis on the correlation exhibited.  The textbook continues the example of a musically gifted child by mentioning that they may be "picked out at school and given special opportunities," such as entrance into music festivals that they did not even apply to.  This is an example of evocative type genotype-environment correlation in that the child does not intentionally expose themselves to such environment(s), but others instead adapt in recognition of the individual's talents.  Likewise, introverts and extroverts do not always have to actively seek out environments conducive to their needs.  Fellow introverts/extroverts may recognize their behavioral similarities with the individual and select them as a friend, or superiors (teachers, bosses, etc.) can recognize these behavioral tendencies and adapt the environment (class, workplace, etc.) so that it its most conducive to their needs.  These behavioral differences are thus amplified in that the individuals are placed in situations where the traits are most blatant and exposed, not to mention in that it is a testament based upon which environment they were placed into in the first place.

3. Active Type
"The active type occurs when individuals select, modify, construct, or reconstruct experiences that are correlated with their genetic propensities."  This type of genotype-environment correlation is possibly the easiest to recognize and understand in that the individual actively seeks and subsists in an environment conducive to their needs, genetic tendencies, and behaviors.  Although others may not have a hand in creating this environment, as they do in passive type and evocative type genotype-environment interaction, the individual can still actively create the environment on their own.  In doing so, the environment that they choose is once again (almost blatantly) representative of their genetic tendencies and behaviors, and their performance and actions in such environment serve as testament to and amplification of these traits.  For example, the textbook mentions that "even if no one does anything about their musical talent, gifted children might seek out their own musical environments by selecting musical friends or otherwise creating musical experiences."  The action of seeking out these environments and friends reveals the character and nature of the individual, and in subsisting in an environment conducive to their genes, the individual portrays their genetic predisposition to musical talent and interest.  The behavioral differences between introverts and extroverts can also be exhibited in this manner, in that their search for friends and a conducive environment reveals their behavioral instincts and innate tendencies, and that their actions in this environment, which is conducive to their traits, are amplified so as to demonstrate the variance of behavior created by the wide variance in environment.

"Passive genotype-environment correlation requires interactions between genetically related individuals.  The evocative type can be induced by anyone who reacts to individuals on the basis of their genetic propensities.  The active type can involve anybody or anything in the environment."  In being able to recognize the different types of genotype-environment correlation, one can identify how an individual's environment was created, as well as what this type means in respects to the individual's genetic tendencies and behaviors (is the environment simply a creation by the parents? is it a product of the reaction by others based on the behaviors of the individual? is it a deliberate choice that the individual seeks to subsist in? how do the individuals, like introverts and extroverts, seem to vary in behavior based on their environment and the tendencies and interests that are amplified?).  Too often, when analyzing the causes of a behavior, individuals immediately cite environment.  However, as environment is a by-product of genotype and behavior, it is at times a device for amplification rather than for cause and effect.  It reveals the differences in choice(s) and action(s) of individuals, which can be directly applied to the contrast in behaviors between introverts and extroverts.

(Rutter)

Next week, as mentioned before, I will be exploring genotype-environment interaction, the partner concept to genotype-environment correlation.  Also, I would greatly appreciate if, before then, you could please participate in my survey regarding the behavioral differences between introverts and extroverts, as well as encourage your friends, peers, and colleagues to participate in it as well.  The link to the survey is below if you would be willing to participate.  Thank you.

https://www.surveymonkey.com/s/62238YL

Works Cited:

"Gene-Environment Interaction."  National Institute of Environmental Health Sciences.  U.S. Department of Health and Human Services, 28 Aug. 2014.  Web.  6 Feb. 2015.
"Heredity."  Certificate Biology.  Certificate Biology, n.d.  Web.  6 Feb. 2015.
Plomin, Robert, John C. DeFries, Valerie S. Knopik, and Jenae M. Neiderhiser.  Behavioral Genetics.  6th ed.  New York: Worth Publishers, 2013.  Print.  Pages 107-118.
Rutter, Michael.  "Why the Different Forms of Gene-Environment Interplay Matter."  SlideShare.  LinkedIn Corporation, 26 Jul. 2010.  Web.  6 Feb. 2015.