A number of twin studies have attempted to compare the relative importance of genetics and environment in the determination of sexual orientation. In a 1991 study, Bailey and Pillard conducted a study of twins recruited from "homophile publications", and found that 52% of monozygotic (MZ) brothers (of whom 59 were questioned) and 22% of the dizygotic (DZ) twins were concordant for homosexuality.[4] 'MZ' indicates identical twins with the same sets of genes and 'DZ' indicates fraternal twins where genes are mixed to an extent similar to that of non-twin siblings. In 2000 Bailey, Dunne and Martin studied a larger sample of 4,901 Australian twins but reported less than half the level of concordance.[5] They found 20% concordance in the male identical or MZ twins and 24% concordance for the female identical or MZ twins. Self reported zygosity, sexual attraction, fantasy and behaviours were assessed by questionnaire and zygosity was serologically checked when in doubt. A meta-study by Hershberger (2001)[6] compares the results of eight different twin studies: among those, all but two showed MZ twins having much higher concordance of sexual orientation than DZ twins, suggesting a non-negligible genetic component. …show more content…
Women showed a statistically non-significant trend to weaker influence of hereditary effects, while men showed no effect of shared environmental effects. The use of all adult twins in Sweden was designed to address the criticism of volunteer studies, in which a potential bias towards participation by gay twins may influence the
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
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.
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.
Interestingly, statistics show that the mothers’ side of the family has a greater influence on gender orientation rather than the fathers. Also noted that over 65% of the candidates who identified as homosexual, their mothers either had none or only one live brother. (4) Comparing myself to this, my mother only has one brother!
Why some people are attracted to members of their own sex whereas others are attracted to members of the opposite sex is no known cause or reason. There is belief to it possible contributing from genetics, hormonal and the environmental influences. One study stated that there is a 50 percent chance that if one identical twin is homosexual or bisexual, the other twin is too. Similar findings lead that some researchers estimate that sexual orientation is 30 to 70 percent genetic (Mustanski, Chivers, & Bailey, 2002).
Conjoined twins are a rare phenomenon. In the even that a set should appear where one twin is dependant upon the other, I believe that they should be separated, at minimum, to save the life of one. At the same time, I believe that every set of conjoined twins is its own special case. In this study, I will present the background information on conjoined twinning, give a few case studies, and give the pros and cons of conjoined twin separation. I will end with my own views on the subject.
I was born a twin and research studies show that with twins there is a high percentage that one twin may have a speech impairment. I was twin (a), the one who had the severe speech impairment. Growing up and not being able to speak properly had a major impact on my life. My speech was so severe that my mother and father use to tell me that they felt bad because they were my parents and they couldn’t understand what I was trying to say. Thanks to my twin sister she knew everything that I was trying to say and she would translate for me. I begin to take speech classes in kindergarten up until I was in the 5th grade. I never knew that my speech problem was so severe until I began school and all the other children begin to laugh and make fun of me because of the way I spoke, they would tell me “I spoke like a baby”.
In this study, they are used several type of method, one of the technique is used two or more test instrument to ensure the adequate coverage, for example the participants were given a battery of personality and mental ability tests, interest and value inventories and psychomotor tests. In addition, separate of examiners administer the IQ test, life history interview, psychiatric interview and sexual life history interview. The twin also complete questionnaire independently under the constant supervision of the staff members. Twin studies are valuable to researchers because identical twins share 100% of their genes and fraternal twins share, on average, 50% of their genes. Both identical and fraternal twins share certain aspects of their environment (e.g. religious practices in the home). This allows researchers to estimate the heritability of certain traits. Participants are asked about academic ability, personality, and interests; family and social relationships; mental and physical health; physiological measurements. Of interest to researchers are prevalence of psychopathology, substance
Nearly 130 bird species have been observed engaging in sexual activities with same-sex partners. While the evolutionary purpose of this behavior is not clear, the fact that animals routinely exhibit same-sex behavior belies the notion that gay sex is not a modern human innovation. Other research has found that being gay or lesbian tends to run in families. It is also more likely for two identical twins, who share all of their genes, to both be gay than it is for two fraternal twins, who share just half of their genes, to both be homosexual. Those studies also suggest that genes seemed to have a greater influence on the sexual orientation of male versus female identical twins. A study detailed an in-depth analysis of blood and saliva samples taken from 409 pairs of openly gay brothers, including non-identical twins, from 384 families. The only common characteristic shared by all 818 men was being gay. Researchers theorized that any single nucleotide polymorphisms consistently found among these men would have something to do with sexual orientation. Sexual brain organization is dependent on sex hormone and neurotransmitter levels occurring during critical developmental periods. Psychologists Michael Bailey and Richard Pillard have studied identical twins who are raised together. "Although all people in all societies with rare exceptions are socialized to be heterosexual, the predictable, universal appearance of
As the tsunamis surging like hurricanes, volcanoes bursting into the sky, mountains crumbling into pieces, the destruction of super continent had begun. I wanted to go to the center of pangea. When I arrived there were scary dinosaurs and other unnatural animals. I ran away as fast as I could, because there animals were dangerous. Fortunately, I found a place to hide in. The weather was very windy and I was barely able to breathe due to the oxygen. It was a terrible and at the same time an intriguing experience, but I tried my best to survive.
As I walk through the crowded mall with my sister, little children stare, most adults do a discreet double take, and some bold adults question us outright. “Wow, are you twins?” “Do you know you look the same?” “What’s it like to be a twin?” “Do you have, like, psychic powers, or something with each other?” These are the most common questions twins hear. Almost all twins don’t really mind them and sometimes the attention is cool. Mostly, we just smile tolerantly at each other and answer them as best we can. After all, we don’t really know how to describe being a twin. We have never known anything else. Nonetheless, here we are. So, as a person who might not know exactly what she is talking
Scientists and psychologists everywhere study twins. The argument most commonly studied is nature versus nurture. The focus of this essay, however, is whether or not to separate twins in schools. Some believe the separation is demeaning and traumatic to the twins. The side about to be proved however that is this separation is a necessary step in the individualization of twins. Often, separation sparks the path to individualization.
The Minnesota Twin Registry started in 1983 and its goal was to establish a registry of all twins born in Minnesota from 1936 to 1955 to be used for psychological research.., T.J. Bouchard, working in conjunction with the University of Minnesota, started exploring the similarities and differences in characteristics like personality, career interests, and a variety of personal interests between identical twins who were reared apart. Research was conducted on twins from all over the world. The Minnesota Twin study gave scientists a new insight of the role of nature vs. nurture on human development and personality; it was the hope that twin studies would be able to tie genes to specific behaviors. From the study, we understand that twins who were separated at birth and raised in different families
“At best genetics is a minor factor,” says Dr. Neil Whitehead, PhD (RSS, 2015). Whitehead worked for the New Zealand government as a scientific researcher, and then spent four years working for the United Nations and International Atomic Energy Agency. His PhD is in biochemistry and statistics. He did his research with identical twins. Identical twins have the same genes or DNA. They are nurtured in the same prenatal conditions. If homosexuality is caused by genetics or prenatal conditions and one twin is homosexual, the other twin should also be homosexual right? Identical twins are
Globalisation is a really widespread topic. There are millions of definitions, opinions, organisations and perspectives because it concerns the whole world. This essay is a try to give some information and to explain my view of the issue.