twin studies Essay

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.

Feist, J., Feist, G. J., & Roberts, T. (2013). Theories of personality (8th ed.). New York, NY: McGraw-Hill.

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.

Feist, J., & Feist, G. J. (2009). Theories of Personality (7th ed.). New York: McGraw-Hill.

The theory to this study was that if you take two people with exactly the same genes, separate them at birth, and put them in completely different environments, the behavioral and personality characteristics that they share as adults can only be explained through genetics. Participants in the study were specifically monozygotic twins who were separated at birth, lived apart from each other for a significant span of their lives, and reunited as adults. Each twin underwent a series of tests and interviews individually so that it was impossible for them to influence their answers.

Psychologist Nancy Segal, who specializes in twin research was quoted saying, "recent twin research showed the genetic contribution to happiness and stability are about 50% and 80% respectively, while life events have only a transitory effect on happiness" (1999.) Segal's conception is not directly concerning human intelligence, yet, if her statement is in fact true, it substantiates some importance of heredity. It also indicates that heredity certainly does have a notable effect on a person. In general, twin studies support the nature side of the debate. If environment (or nurture, for that matter) didn't play a part in determining an individual's traits and behaviors, then identical twins should, theoretically, be exactly the same in all respects, even if reared apart. But a number of studies show that they are never exactly alike, even though they are remarkably similar in most respects.

According to the Psychiatry and Behavioral Sciences department at John Hopkins University, extensive studies have been done on twins and families, to display the finding

‘Heritability’ refers to how far genetic differences are responsible for variations in traits, characteristics or abilities within a population. Heritability studies may involve twins or adopted children, where it might be possible to distinguish between genetics and environmental influence. These studies generally find that monozygotic twins are more intellectually akin than dizygotic twins; similarly children who have been adopted, remain intellectually comparable with their biological parents. This infers that there must be a genetic component responsible for differences in intelligence. However heritability estimates are inconclusive. (Deary 2001) claims that the heritability estimate tends to be placed between 40% and

Across studies of 10,000 twins, the intelligence test scores of identical twins reared together are virtually as similar as those of the same person taking the same test twice…Likewise, the test scores of identical twins reared separately are similar enough to lead twin researcher Thomas Bouchard (1996) to estimate that ‘about 70 percent’ of intelligence score variation ‘can be attributed to genetic variation. (p. 455)

Twins are sought to be an interesting set of individuals and many questions can surround the theories of twins and their IQ, mental states, and the psychological tolls it may have on them and their families. Many parents can barely handle a singleton and would find twins birth a more challenging surprise. Some people believe that the IQ and mental state of the twins could come from their birth rate which at many times is low or the family dynamic for which the twins are raised. Many twins depend on each other in order to learn and develop which could have some advantages and disadvantages among their growth. Singleton children may have older or younger siblings or surround themselves with a group of different types of age groups and grow from there, but twins are at times more of a loner and like to stay among each other which have been my experience with my twins. Identical twins as oppose to fraternal also has an effect of the psychological and IQ of each of them. Fraternal twins are more like singletons for the most part because they do not share a egg where as the identical twins( which is have) develop differently and have a closer bond because they share the same egg and were actually a single egg that was split into two eggs.

Neubauer also recognized the exceptional research possibilities such a separation offered. Studies of twins reared apart are one of the most powerful tools that scholars have to analyze the relative contributions of heredity and environment to the makeup of individual human natures. Identical twins are rare, however, and twins who have been separated and brought up in different families are particularly unusual. Neubauer was aware of a mere handful of studies examining twins reared apart, and in most cases the twins being studied had been separated for only part of their childhoods and were reunited at some point long before the study began. Here was an opportunity to look at twins from the moment they were separated, and to trace them through childhood, observing at each stage of development the parallel or diverging courses of their lives. Because the

After birth, the twin babies become even closer. A mother of fraternal twins, Sherry Warner, agrees that twins share a bond other siblings don’t from the day they are born; “The girls were the best of friends from the moment they were born. It seemed the only thing fought for was attention” (Warner). Some twin babies are even said to have created their own language that only they understand. Even Sherry Warner said her twins had their own incomprehensible language. Based on an excerpt from the Acta Geneticae Medicae et Gemellologiae Twin Research, it is possible twins do in fact have their own language: “These “autonomous languages” exist in 40% of all twins, but often disappear soon” (“Language”). The creation of these languages at an age in which