Twin Early Development Study: Nature versus Nurture

There are numerous “nature” vs. “nurture” beliefs/perceptions that are commonly debated within our society. One highly debated and controversial topic is homosexuality. Homosexuals believe their sexual attraction to other people of their own sex is innate and alike their other human traits (e.g. eye color, gender and athleticism) are assigned to them by their genes (nature).

For more than a century after Galton’s observation, twin studies have become an essential tool when studying behavioural genetics. It allows researchers to understand how genetics and the environment play a role in an individual’s development which include biological, behavioural and psychological disorders. Thus twin study is used to evaluate the degree of genetic relatedness and is commonly used to explore the influence of environment and genes when studying patterns of aggression, intelligence, schizophrenia, and even alcohol dependence.

In “Barbie Girls versus Sea Monsters,” Messner argues that differences in gender and gendered actions are not caused by innate differences between males and females but are caused by social constructions of gender. Gender socialisation occurs on three levels: cultural, structural and interaction. I believe the argument is compelling. Men and women or boys and girls acting in ways that are deemed gender specific is not the action of individuals or the gender, but the effects of society and society’s construction of gender.

Identical twins may share the same DNA make up and grow up in the same household, yet they have very distinct personalities. On the other hand, twins that may have been separated at birth, find that years later when they meet up for the first time that they have very similar character traits and experiences. Researchers have been trying to figure out for years if DNA or environment has a bigger factor in determining a twin’s personality. When researchers try to determine how personalities are developed, they often look to twin studies to determine if DNA or life experiences are influential in personality development.

The old and popular debate between ‘nature vs. nurture’ has generated a lot of interest in newborns, who were previously thought to be ‘blank slates’, and has contributed a lot to developmental psychology, a field of psychology focusing on studying infants. It is now generally accepted that both nature and nurture make equal contribution to the infant’s development.

The nature- nurture debate has many different case studies, which often questions environmental and hereditary aspects of the nature- nurture debate. A tangent which is focused on in this essay is how the case studies of schizophrenia and IQ, specifically affect twin and adoption studies. This essay will firstly, give a brief outline of the nature-nurture debate and the definitions of twin and adoption studies. Secondly, it will illustrate two main case studies, which are IQ and Schizophrenia studies. Thirdly, will contrast and compare the two and research’s impact on the case studies in regards to nature vs. nurture and finally, will conclude with the impact of the nature-nurture debate and twin and adoption studies.

Theoretical Propositions: The question of why people are who they are and why they behave the in the way that they do was asked. The researchers wanted to understand if people develop into who they are primarily from factors in the environment or because of there genetic makeup. In the second half of the 20th century most psychologists agreed in the theory of behaviorism, human behavior is caused only by factors in the environment. This study would answer the common “nurture vs nature” question that many people still ask today.

For many years psychologist, sociologists, novelist, students, people in general have debated over which side, nature or nurture makes us who we are. Each side of the debate has compelling arguments and facts to support their claims, however it is foolish to say one has a greater impact than the other. I believe that humans are the product of society and biology, and that they come hand in hand. That both nature and nurture make us human because there are too many facts from each side of the argument to say that one is more influential than the other. Our biology is what differentiates males and females, and our sense of self develops from the interaction with other humans and society.

Once a child is born and their development continues, then starts the controversy and wonder as to whether how the child is raised effects their outcome in adult hood, or whether they are just born to be a certain way. Child psychology looks into the many different factors that affect the pregnancy and raising a child. Such as, parenting styles, and how the environment (nurture) and the genetics (nature) play an important role in the child’s development.

In the nature versus nurture debate, homosexual’s environment and experiences shaped them more than genetics. For example, being raised in a gay home will heavily influence someone’s orientation unconsciously. Also, if an individual ties abuse and trauma from the opposite sex this fear might trigger them to feel more comfortable or attracted to the same sex. In addition, a person’s curiosity to experiment with their sexual preferences also can alter what they initially once were attracted to. A person’s experience is a vital role of how one’s sexuality is developed.

If sexuality is developed at an early stage in a person’s life, then how does homosexuality occur? Homosexuality in Darwin’s selection theory doesn’t even exist. (Roughgarden, 2009, 127) Some say that it’s based on the person’s surrounding environment and influences while others say that it’s purely genetic. There has been substantial evidence that points to both genetic and environmental factors in developing homosexuality, but no one factor that clearly pushes over the top to define the origins of homosexuality. Statistically if a male is straight then there is a 4% percent chance that his brother might be gay, but if the male himself is gay, then the percentage jumps to 22%. (Roughgarden 2009: 247) These statistics simply show that gay males tend to group in families, it doesn’t necessarily point out anything specific about the environment’s effects or the male’s genetic makeup. (Roughgarden, 2009, 247)

Homosexuality is at the front lines of the nature versus nurture debate. Many studies have been conducted, but a clear cause has yet to be found. Anti-homosexuals, consisting mainly of religious groups, believe that homosexuality is abnormal, unnatural, and can be changed. Because of their beliefs, homosexuality must be a learned behavior. Whether homosexuality is biological or learned behavior is still a mystery, but scientists are finding more evidence to suggest the former.

One of which is not the oldest, one of the oldest arguments in the history of psychology: the nature or nurture debate. This debate within psychology is concerned with the extent to which particular aspects of behavior are a product of either inherited or acquired characteristics. Nature, in this aspect, refers to the what we think of as the ‘pre-wiring’ and is influenced by genetic inheritance and other biological factors. Proponents of this believe that homosexuality is inherited, that personalities are result of an evolutionary process, and that people inherit their behaviors because of a complex, intricate genetic interactions. Proponents believe that it is our genes that governs and dictates our behavior. Therefore, an individual behaves the way he is because he is bounded to be that way, he is ‘wired’ to be that way. With respect to homosexuality, this biological perspective explains it as genetic predisposition, just like the color of a person’s eyes. In contrast, nurture, in this aspect, is referred to thee influence of external factors after birth, the environment, in general. This debate sparkled the interest of scientists, and started to which we can account homosexuality

There are a plethora of ideas and theories regarding the developmental psychology behind why people metamorphosize into different personalities and habits later in life. Developmental psychologists have developed several ways to try and determine where the determining factors are in peoples’ lives that cause the differences. Several of the theories tend to have overlaps in parts of the ideas such as the ideas of “nature vs nurture” and that of “social context.” These theories share the overlapping ideas that there are outside influences on the way a person turns out in life. While “nature vs nurture” states that there are outside influences, there is also a counterargument that the genetic make-up of a person is the determining factor for how that person develops later. Even still, there are some who also believe that both arguments of “nature vs nurture” have even attributes on the lives of people.

This question has perplexed psychology and behavioural scholars for many years, and although it begs a straightforward answer, the reality is not. The question often reverts to a fundamental belief of nature or nurture, when in reality the answer lies somewhere in the combination of the two.