Dizygotic Twins

Identical twins are many times seen as genetic reproductions representing variations from twin to the other twin and are created because of environmental factors (Cervone & Pervin, 2010). Since identical twins share identical genetics, his or her personality seems to also share similarities. Moreover, the environment can impact fraternal twins, resulting in fraternal twins personalities and his or her characteristics similar to each other. For example, identical twins. Some research shows twins that are raised in the same residence have little differences from those who are raised in a different home.

For major depression between monozygotic and dizygotic twins suggest a heritability of about 37%. It is lower than the heritability of bipolar disorder or schizophrenias.

Table 3-1 examines the correlations between selected characteristics for the identical twins separated at birth and the twins raised together. When compared to each other, they both have very similar brain wave activity, blood pressure and heart rate in the physiological characteristics. The Raven intelligence test was very similar, but the WAIS IQ displayed a bit of difference when compared to the other comparisons made. Personality wise, they typically had similar personalities at the same rate as twins raised together. Psychological interests were off a little bit, but still very similar. The twins that were separated at birth had less similar psychological interests compared to the twins

Parallel to this, the focus on genetics is Particularly convicted in twin studies, which establish a comparison between monozygotic twins that are identical and dizygotic twins, which are opposingly non-identical. This distinction can be identified in Torgersens study, which compared MZ and same sex DZ twins where one proband had an anxiety disorder, and it was discovered that such disorders were 5x more frequent in MZ twin pairs, who mutually shared identical genetics.

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

Twins, share a bond that no parent, child or sibling relationship can ever compare. There are two main types of twins, and these include: monozygotic (identical) twins and dizygotic (fraternal) twins, and they are compared by their emotional, behavioural, and cognitive similarities. (Robert Plomin, 1997). According to Social Issues Referencing, 2007, whereas Identical twins are formed from a single (mono) zygote and are genetic “carbon copies”, fraternal twins develop from two (di) separate zygotes, as a result of two eggs being fertilized by two sperms independently. (Social Issues Referencing, 2007, para. 8)

As Joseph (2004) pointed out, however, this is not always the case. Monozygotic twins are more likely to be treated in a similar way, encounter more similar environments, and be to be thought of as ‘the twins’ rather than two separate individuals. This, in turn, can lead to ‘identity confusion’ and so potentially a higher concordance rate amongst monozygotic twins. Therefore Joseph argues that the greater concordance rate seen in monozygotic twins than in dizygotic twins is a result of the differing attitudes and environments experienced by the two types of twins.

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.

Twin studies have been a large part of the growing debate on whether genetics or environment (nature v. nature) is responsible for the cognitive, socio-cultural and biological development. In order to properly assess twin studies it is important to know why and how they are relevant in psychology. Identical twins are especially effective in research particularly in the field of developmental psychology and behavioral genetics due to the monozygotic genes which means they originate from a single zygote (fertilized egg) which essentially means they share 100% of the same genes. Due to this exact copy of genes between twins means this can be efficiently be used in order to observe the impact of

I study was preformed by Janicak et al 2001; they found that monozygotic twins have a 48% concordance rate. This is considerably less in dizygotic twins where the concordance rate falls to 17%. This would suggest there is a strong case for genetics being involved with

Identical twin studies are most useful in determining genetic influence on intelligence. Since the identical twins share the same exact genes, the straightforward comparison of intelligence can display if this human trait is truly heritable. Similarity of intelligence scores between identical twins supports the genetic influence on intelligence. According to Myers (2007),

There are two types of twins. One type of twins, called identical twins, is exact clones of each other. They share the same DNA and were made from a single split egg. More research as been done regarding these types of twins as they are the more remarkable kind. Since they are a genetic match, nature plays the

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.