Heredity Versus Environment: Twin, Adoption, And Family Studies

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.

“Trying to separate out nature and nurture as explanations for behavior, as in classic genetic studies of twins and families, is now said to be both impossible and unproductive” (Levitt, 1). Social scientists have declared the nature-nurture debate to be unnecessary. Similarly, scientists feel that such debate is not only unhelpful, but also outdated. From geneticists’ perspective, nurture and nature interact to influence

The classic debated topic of Nature versus Nurture has been and will always be a quarrelsome subject in the scientific world. Meaning, the issue of the level to which environment and heredity sway behavior and development in a person. Nature can be defined as, behaviors due to heredity. This means the behaviors is based on the inherited makeup of an individual and is an influence of the growth and development of that individuals’ all through life. On the other hand nurture is causes of behaviors that are environmental. This Intel’s the influence is from the individual’s parents, siblings, family, friends and all other experiences that individual exposed to during life. However, these concept of ideas supports the inborn genetic framework,

Twin studies are a mainstay of the nature verse nurture debate because they allow researchers to conduct “natural experiments” on human beings. When researchers try to determine the relative importance of genetics and environment with regard to a certain condition, they have a hard time because they cannot generally get people with the same genes. This is where twin studies come in. Twins studies are part of the method used in behaviour genetics, which includes all data that are genetically informative. E.g. siblings, adoptees, pedigree data etc. Researchers use this method to estimate the heritability of traits and to quantify the effect of a person 's shared environment (family) and unique environment (the individual events that shape a life) on a trait.

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.

In reading stories about identical twins my point of view is easily understood. Various types of psychologist have analyzed the study of identical twins. It shows that individuals with the same genetic make-up can be totally different, when it comes to personality. Nurture promotes the twins to grow up as separate individuals. Its a lot better if a twin has his or her own personality rather than the same exact personality of the other half. I think this great debate weighs heavier on the nurture side. As a child my parents, and sibling overshadowed my genetic make-up. No matter how much I thought my physical traits made me behave. It did not affect me more than the things that I had seen and been exposed to. The more things that I had seen around and experienced made me the person that I am today. If my genetic make-up was totally different, to a certain extent, I am sure that I?d behave the same way that I do presently. There are exceptions to that. For instance if I were six foot five and one hundred and ninety pounds, I?d most likely be in the NBA and be really rich. I think if I was really rich and in the NBA I wouldn?t have the same worries that I have today. Even if before I were in the NBA I would have lots of attention and have a lot more confidence. So to an extent I would change a little if my genetic make-up were different. In a sense, genetic make-up is just a competitor to the environmental factors

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.

According to Begley, identical twins are not always identical in behavior just because of genes. Some studies show that when twins are given different circumstances, for example, different educational opportunities, different results are obtained. One example in Newsweek showed one twin may grow to be a professional pianist while the other twin was not at all musical even though the twins were both raised in a musical environment ("Heredity" 69). Twins have different interest from each other, and express them in individual ways.

Human behavior is a loosely defined foundation for individuality, generally considered to be influenced and developed by the environment. However, recent molecular studies have exposed genetic factors that suggest a more biological origin for behavior. Gene segments in the genome of humans and other animals have been identified and associated with particular behavioral traits. Is it possible that the presence or absence of even a single gene may predispose one to alcoholism, increased irritability, or enhanced intelligence? Clearly exploration of the nature versus nurture argument with regard to genetic predisposition has social, political, and legal significance.

The Origins of Morality: How Nature, Nurture, and Especially Free Will Influence One’s Moral Framework

This study showed completely different results than expected. Scientists expected the twins to have low academic achievements and low test scores. This prediction was right for only one of the twins, however the other twin had many academic achievements and an extremely high GPA. The twin with the high GPA had a great helpful attitude and would help anyone in a heartbeat, whereas the other twin did not really have a care in the world and didn’t care what people thought about him or what his grades were. This study proves my point exactly, it is not hereditary and you do not learn your behaviour, you choose

Another study that has been done was with separated twins. Each twin was raised in a completely different environment than the other. Genetically, they were both identical in every way, but the environment that they were raised in was very different. One twin was raised in a very hostile setting and slowly became violent as an adult while the other twin was

Siblings, both biological and adopted, are a prime example of how environment is the supreme factor in determining traits and behavior. Siblings share similar genes and/or environments which provides an ideal and objective base for research (Cool, "Twins, Nature and Nurture"). Separated siblings with a similar genetic makeup are no more likely to have similar personalities with one another than with anyone else. Research conducted by Nancy Pedersen and her colleges on 99 separated identical twins, when compared to an equal number of identical twins that were raised together, showed that separated identical twins had less identical personalities than twins brought up in the same environment (Pedersen, p.950-957). Twins separated at birth had

Controversy arises when nature (inheritance) is combated against nurture (environment). This controversy began with the development of the behavioristic point of view. “Behaviorism arose as a protest against all form of “introspective psychology,” which was concerned with mental states such as consciousness and will”(Plomin 3). It led to an environmentalism that rejected the possibility of genetics influences on behavior. The burden of explaining individual differences fell completely to environmental factors. Genetics involve genes, which are chemical structures that control the production of proteins, thereby indirectly affecting

From these studies, researchers have found that twins who have grown up in the same household share similarities in the way they think, act, dress, speak, etcetera. However, with the first type of twin studies, researchers could not differentiate whether the similarities were due to them having identical/similar genetic makeups or growing up in the same environments. Therefore, in order for psychologists to know whether similarities in twins are genetic or socially influenced, they studied twins who grew up in completely different households and environments. The study showed that despite growing up with a different family and in a different environment, they still had noticeable similarities in fashion, interests, and thought processes (K.W. Brown, personal communication, August 29, 2017). Twin studies, as well as other studies, have greatly contributed to our understanding of overall role that genes play in the development of psychological traits and behavior.