Francis Galton Twins
In 1875, Sir Francis Galton presented the twin study in his article “The History of Twins, as a Criterion of the Relative Powers of Nature and Nurture”. In the article, Galton bares his claim of the importance of twins and the serendipitous life experiment that takes place throughout their lives. This serendipitous experiment he is referring to, is the effects of nature and nurture, or, propensities obtained at birth and those that were created by environment and circumstance. Twin studies performed today must give credit to Galton and his ideas and practices. Today, researchers can compare a breadth of different outcomes of twin research; identical (monozygotic) versus fraternal (dizygotic) twins, comparing adopted children to their adoptive
…show more content…
and biological parents, and monozygotic twins raised together versus raised separately. These methods, twin studies together with adoption studies, is the most effective way to understand the relationship between inheritance and circumstance. This paper will show the influential impact of Galton’s ideas on studies performed still today. Keywords: Galton, nature vs. nurture, heritability, twins, adoption
Sir Francis Galton: The Apostle of Quantification
Historical Background
Francis Galton was born in the United Kingdom in 1822 and would grow to be one of the most influential minds in science. At an early age, Galton was a curious and intelligent boy. These characteristics would blossom into a love of several diverse areas of study, particularly in science. He was an accomplished pioneer in fields from weather mapping to fingerprinting (Goodwin, 2011). Galton claimed, even as a young adult, that his intelligence was based on an inherited superiority. He furthered this conclusion in 1859 after his cousin, Charles Darwin, published his findings on evolution (Goodwin, 2011). He saw that if there were certain traits that were carried over to offspring to ensure survival in plants and animals, then intelligence must be a trait to help ensure the physically weaker humans still have offspring (Goodwin, 2011, p. 152). Galton furthered this claim of innate intelligence in his work Hereditary Genius, published in 1869. Galton had a special love for quantification and statistical analysis, in which he used to help support his claim. By looking at the family trees of certain prominent figures in Great Britain, he deduced that the prominence was no coincidence and that intelligence was caused by evolution, not by the environment.
During this time, not everyone was on board with Galton’s notion of intelligence being an evolutionary force. Alphonse de Candolle, a highly prominent Swiss botanist, believed Galton was overlooking the importance of environmental factors. Candolle conducted his own study to negate Galton’s theory. While Candolle did show the importance of environmental factors, Galton performed another study, to strengthen his claim. In this new study, Galton would coin the phrase that is still echoed in psychology classrooms across the world: Nature vs Nurture. In doing so, Galton created two methodological techniques still in use today: the survey method and twin studies (Goodwin, 2011, p. 153). In his survey, Galton asked 180 members of the Royal Society, to describe several aspects of their upbringing. After the study was complete, Galton recognized that the environment had a major influence on shaping some of the members Royal Society. However, he still remained convinced and concluded that intelligence was inherited.
In his twin studies, Galton found more evidence that suggested that his heritability beliefs were correct. After surveying 94 pairs of twins about particular attributes, he found many similarities in twins that had grown up in separate environments (Goodwin, 2011, p. 153).
Darwin’s Influence on Galton Charles Darwin was a very influential figure, but no one was more influenced by Darwin than his cousin.
In his autobiography Memories of My Life (1908), Galton said of his cousin, “The publication in 1859 of The Origin of Species by Charles Darwin made a marked epoch in my own mental development, as it did in that of human thought generally” (p. 287). Galton was particularly interested in the chapter of breeding animals to promote the best traits. This would eventually lead Galton to the area of eugenics, the selective breeding of humans for superiority. The atrocities that were performed by the Nazi’s in the 1930’s and 40’s using eugenics will not be discussed in this paper, but it is important to note that Galton believed humanity could be improved by selective …show more content…
breeding. After reading The Origin of Species, Galton’s interests in researching humans took over his career. He began a series of different studies and projects to study human characteristics, both physically and developmentally, for the purpose of understanding the differences between people. For example, Galton was the first to recognize humans had unique fingerprints, different from everyone on earth. This breakthrough was eventually used by Scotland Yard and other law enforcement agencies to identify people during investigations. Concept of Nature vs. Nurture The concept of nature vs.
nurture has been important part of psychology since Galton coined the term in 1874. As mentioned before, Galton did recognize that there were some environmental (nurture) forces that contributed in shaping a person. However, he believed more in the inherent (nature) forces that determined a person’s characteristics, specifically intelligence. There is strong evidence that suggests that both are be at play, and some researchers can argue one more than the other. When Galton performed his study of the prevalence of prominent men and their family trees among the general population, he concluded that the higher rate of prominence in eminent men were due to inherent or evolutionary traits, rather than environmental
forces. Galton believed that
Rational of Twin and Adoption Studies Galton was the first to study the individual differences in humans and his efforts are still very much a part of today’s society (fingerprinting, surveying, twin studies, etc.). In order to obtain a pure study of the heritability of human characteristics, researchers must use adoption studies, to avoid any environmental (nurture) similarities between biological relatives. Characteristics can include an individual’s prevalence in depression, anxiety, cancer, or plethora of other characteristics. What’s more, researchers can also study personality traits such as IQ and temperament, as well as many other behaviors like substance abuse.
In the most perfect condition for these types of studies, researchers would want identical twins that were raised in separate environments. In doing so, the study would show two individuals with the same set of DNA mapping but with separate environmental forces that potentially could have helped shape the individual. Alternatively, researchers can also study fraternal twins, who only share half of their segregating genes. In both types of studies, researchers can see the influence of both genetic and environmental factors that play a role in human development (Eley, 2001).
Methods of Studying Heritability of Human Characteristics
Today, there are several ways to study heritable characteristics and behavior. One such way that is used often among researchers is the Galton inspired questionnaire or survey. In one questionnaire, Ask et al., phrased several questions to parents such as: “People tell me I worry too much” or “I often worry about things in the future” etc., and parents then were to rate these phrases for their children on a 3 point scale: 0 (not true or hardly ever true), 1 (sometimes true), 2 (true or often true).
In another study done by Bohlken et al., monozygotic and dizygotic twins were used to determine the heritable behavioral phenotypes such as intelligence and schizophrenia. In their study, structural network mapping was examined using MRI’s and brain scanning. After creating a map of the different regions of the brain, the researchers were able to pin point the specific nodes and anatomical regions of the affected areas of the participant.
The most ideal design for observing the environmental and inheritable differences between twins would be a longitudinal design. In a longitudinal design, participants are questioned, surveyed, or observed throughout a long period of time, say several years. In doing this type of study, researchers can see what environmental effects have occurred, specifically on identical twins reared in separate environments. For example, identical twins that have been adopted by different parents.
Twin Studies
There are many twin studies that have been performed that showed the different outcomes of twins that were reared together and those who were reared apart. One study, by Ask, Torgersen, Seglem, and Waaktaar, was done to look at the genetic and environmental causes of variation in adolescent anxiety symptoms. The main goal of Ask et al. was to estimate genetic and environmental influences using a multi-informant design with responses from a population-based sample of adolescent twins and their family (Ask et al.). In 2006 the researchers invited 1,394 Norwegian born twins, ages 12-18 years old, and their parents, to participate in the study. The Norwegian Medical Birth Registry provided the researchers with addresses and names of all twins born in Norway from 1988-1994. With the approval of the families, questionnaires were sent to twins to fill out. The same questionnaires were sent to both parents and they were asked to fill out the questionnaire for each twin. On the questionnaire, researchers phrased several such as: “People tell me I worry too much” or “I often worry about things in the future” etc., and parents then were to rate these phrases for their children on a 3-point scale: 0 (not true or hardly ever true), 1 (sometimes true), 2 (true or often true). The symptoms of anxiety were measured by using the Screen for Anxiety-Related Emotional Disorder questionnaire, known as SCARED, for the last year. Using the data from the multiple raters (the twins and their parents) their study showed reliable indicators of the genetic and environmental influences on variation in anxiety symptoms in adolescent twins (Ask et al.). Researchers used the Common Pathway model, to define the hidden symptoms of the differences between the twins and their parents. Researchers found that genetic (nature) factors were highly influential in determining the anxiety symptoms. However, the environmental (nurture) factors differed in determining anxiety symptoms, therefore showing the genetic factors were more influential. Galton would agree with the findings, saying that genetic outcomes are more influential than environmental. In another study done by Livingstone, Conventry, Corley, Willcutt, Samuelsson, Olson, and Byrne, showed that environmental factors do have an effect on monozygotic twin children. As the research team explained, environmental factors play a key role in the development of children with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the long-term effects of such factors are still uncertain. In the study, the team used 1,024 monozygotic twins (490 make, 534 female) with an approximate age of 5. The participants were gathered from twin registries from Australia, Colorado, Norway, and Sweden. Although the team also gathered data from dizygotic twins, only the data from the monozygotic twins was included in the study. To assess the symptoms of ADHD children, the team used the Disruptive Behavior Rating Scale (DBRS; Barkely and Murphy, 1998). Using the Galton pioneering method of surveying, the research team had the parents of each twin fill out nine questions to assess the children impulsivity and nine questions to assess the child’s inattention. Using four possible answers to code: (0) not at all, (1) just a little, (2) pretty much, and (3) very much, parents were asked to complete the form. Then, a one-year retest was performed, using the same questionnaire. In their study, the results indicated that there was a link between environmental influences during early childhood and the lasting effects of ADHD symptoms. Over half of the environmental differences in inattention and hyperactivity disappeared over time, rather than remaining stable (Livingstone et al.). In an effort to further the insight on the nature-nurture question, in 2014, researchers Scaini, Belotti, and Ogliari, examined the relationship between social anxiety disorders and the genetic and environmental influences on individuals of different ages. As the team pointed out, anxiety disorders, specifically social anxiety disorders, are the most common psychiatric illnesses. Social anxiety disorders, or SAD, is characterized by “a marked and persistent fear of one or more social situations in which the person is exposed to unfamiliar people or to possible scrutiny by other, marked fear or anxiety about one or more social situations in which the individual is exposed to possible scrutiny by others” (American Psychiatric Association, 2013). Here, the research team wanted to explore the genetic and environmental contributions to social anxiety disorders.
Studying classic twin studies, the team used a meta-analysis. From the selected papers the team used, 13 cohorts were obtained for a total of 45,585 individuals, regardless of age. However, some parts of the cohorts were examined according to age, which found a more evolutionary influence estimate for social anxiety disorders in children as high as 54%, with the remaining variances being attributed to non-genetic, or environmental factors (Scaini et al.).
As the results indicated, genetic and non-shared environmental factors were substantially consistent of variance in different phenotypes
and biological parents, and monozygotic twins raised together versus raised separately. These methods, twin studies together with adoption studies, is the most effective way to understand the relationship between inheritance and circumstance. This paper will show the influential impact of Galton’s ideas on studies performed still today. Keywords: Galton, nature vs. nurture, heritability, twins, adoption
Sir Francis Galton: The Apostle of Quantification
Historical Background
Francis Galton was born in the United Kingdom in 1822 and would grow to be one of the most influential minds in science. At an early age, Galton was a curious and intelligent boy. These characteristics would blossom into a love of several diverse areas of study, particularly in science. He was an accomplished pioneer in fields from weather mapping to fingerprinting (Goodwin, 2011). Galton claimed, even as a young adult, that his intelligence was based on an inherited superiority. He furthered this conclusion in 1859 after his cousin, Charles Darwin, published his findings on evolution (Goodwin, 2011). He saw that if there were certain traits that were carried over to offspring to ensure survival in plants and animals, then intelligence must be a trait to help ensure the physically weaker humans still have offspring (Goodwin, 2011, p. 152). Galton furthered this claim of innate intelligence in his work Hereditary Genius, published in 1869. Galton had a special love for quantification and statistical analysis, in which he used to help support his claim. By looking at the family trees of certain prominent figures in Great Britain, he deduced that the prominence was no coincidence and that intelligence was caused by evolution, not by the environment.
During this time, not everyone was on board with Galton’s notion of intelligence being an evolutionary force. Alphonse de Candolle, a highly prominent Swiss botanist, believed Galton was overlooking the importance of environmental factors. Candolle conducted his own study to negate Galton’s theory. While Candolle did show the importance of environmental factors, Galton performed another study, to strengthen his claim. In this new study, Galton would coin the phrase that is still echoed in psychology classrooms across the world: Nature vs Nurture. In doing so, Galton created two methodological techniques still in use today: the survey method and twin studies (Goodwin, 2011, p. 153). In his survey, Galton asked 180 members of the Royal Society, to describe several aspects of their upbringing. After the study was complete, Galton recognized that the environment had a major influence on shaping some of the members Royal Society. However, he still remained convinced and concluded that intelligence was inherited.
In his twin studies, Galton found more evidence that suggested that his heritability beliefs were correct. After surveying 94 pairs of twins about particular attributes, he found many similarities in twins that had grown up in separate environments (Goodwin, 2011, p. 153).
Darwin’s Influence on Galton Charles Darwin was a very influential figure, but no one was more influenced by Darwin than his cousin.
In his autobiography Memories of My Life (1908), Galton said of his cousin, “The publication in 1859 of The Origin of Species by Charles Darwin made a marked epoch in my own mental development, as it did in that of human thought generally” (p. 287). Galton was particularly interested in the chapter of breeding animals to promote the best traits. This would eventually lead Galton to the area of eugenics, the selective breeding of humans for superiority. The atrocities that were performed by the Nazi’s in the 1930’s and 40’s using eugenics will not be discussed in this paper, but it is important to note that Galton believed humanity could be improved by selective …show more content…
breeding. After reading The Origin of Species, Galton’s interests in researching humans took over his career. He began a series of different studies and projects to study human characteristics, both physically and developmentally, for the purpose of understanding the differences between people. For example, Galton was the first to recognize humans had unique fingerprints, different from everyone on earth. This breakthrough was eventually used by Scotland Yard and other law enforcement agencies to identify people during investigations. Concept of Nature vs. Nurture The concept of nature vs.
nurture has been important part of psychology since Galton coined the term in 1874. As mentioned before, Galton did recognize that there were some environmental (nurture) forces that contributed in shaping a person. However, he believed more in the inherent (nature) forces that determined a person’s characteristics, specifically intelligence. There is strong evidence that suggests that both are be at play, and some researchers can argue one more than the other. When Galton performed his study of the prevalence of prominent men and their family trees among the general population, he concluded that the higher rate of prominence in eminent men were due to inherent or evolutionary traits, rather than environmental
forces. Galton believed that
Rational of Twin and Adoption Studies Galton was the first to study the individual differences in humans and his efforts are still very much a part of today’s society (fingerprinting, surveying, twin studies, etc.). In order to obtain a pure study of the heritability of human characteristics, researchers must use adoption studies, to avoid any environmental (nurture) similarities between biological relatives. Characteristics can include an individual’s prevalence in depression, anxiety, cancer, or plethora of other characteristics. What’s more, researchers can also study personality traits such as IQ and temperament, as well as many other behaviors like substance abuse.
In the most perfect condition for these types of studies, researchers would want identical twins that were raised in separate environments. In doing so, the study would show two individuals with the same set of DNA mapping but with separate environmental forces that potentially could have helped shape the individual. Alternatively, researchers can also study fraternal twins, who only share half of their segregating genes. In both types of studies, researchers can see the influence of both genetic and environmental factors that play a role in human development (Eley, 2001).
Methods of Studying Heritability of Human Characteristics
Today, there are several ways to study heritable characteristics and behavior. One such way that is used often among researchers is the Galton inspired questionnaire or survey. In one questionnaire, Ask et al., phrased several questions to parents such as: “People tell me I worry too much” or “I often worry about things in the future” etc., and parents then were to rate these phrases for their children on a 3 point scale: 0 (not true or hardly ever true), 1 (sometimes true), 2 (true or often true).
In another study done by Bohlken et al., monozygotic and dizygotic twins were used to determine the heritable behavioral phenotypes such as intelligence and schizophrenia. In their study, structural network mapping was examined using MRI’s and brain scanning. After creating a map of the different regions of the brain, the researchers were able to pin point the specific nodes and anatomical regions of the affected areas of the participant.
The most ideal design for observing the environmental and inheritable differences between twins would be a longitudinal design. In a longitudinal design, participants are questioned, surveyed, or observed throughout a long period of time, say several years. In doing this type of study, researchers can see what environmental effects have occurred, specifically on identical twins reared in separate environments. For example, identical twins that have been adopted by different parents.
Twin Studies
There are many twin studies that have been performed that showed the different outcomes of twins that were reared together and those who were reared apart. One study, by Ask, Torgersen, Seglem, and Waaktaar, was done to look at the genetic and environmental causes of variation in adolescent anxiety symptoms. The main goal of Ask et al. was to estimate genetic and environmental influences using a multi-informant design with responses from a population-based sample of adolescent twins and their family (Ask et al.). In 2006 the researchers invited 1,394 Norwegian born twins, ages 12-18 years old, and their parents, to participate in the study. The Norwegian Medical Birth Registry provided the researchers with addresses and names of all twins born in Norway from 1988-1994. With the approval of the families, questionnaires were sent to twins to fill out. The same questionnaires were sent to both parents and they were asked to fill out the questionnaire for each twin. On the questionnaire, researchers phrased several such as: “People tell me I worry too much” or “I often worry about things in the future” etc., and parents then were to rate these phrases for their children on a 3-point scale: 0 (not true or hardly ever true), 1 (sometimes true), 2 (true or often true). The symptoms of anxiety were measured by using the Screen for Anxiety-Related Emotional Disorder questionnaire, known as SCARED, for the last year. Using the data from the multiple raters (the twins and their parents) their study showed reliable indicators of the genetic and environmental influences on variation in anxiety symptoms in adolescent twins (Ask et al.). Researchers used the Common Pathway model, to define the hidden symptoms of the differences between the twins and their parents. Researchers found that genetic (nature) factors were highly influential in determining the anxiety symptoms. However, the environmental (nurture) factors differed in determining anxiety symptoms, therefore showing the genetic factors were more influential. Galton would agree with the findings, saying that genetic outcomes are more influential than environmental. In another study done by Livingstone, Conventry, Corley, Willcutt, Samuelsson, Olson, and Byrne, showed that environmental factors do have an effect on monozygotic twin children. As the research team explained, environmental factors play a key role in the development of children with Attention-Deficit/Hyperactivity Disorder (ADHD). However, the long-term effects of such factors are still uncertain. In the study, the team used 1,024 monozygotic twins (490 make, 534 female) with an approximate age of 5. The participants were gathered from twin registries from Australia, Colorado, Norway, and Sweden. Although the team also gathered data from dizygotic twins, only the data from the monozygotic twins was included in the study. To assess the symptoms of ADHD children, the team used the Disruptive Behavior Rating Scale (DBRS; Barkely and Murphy, 1998). Using the Galton pioneering method of surveying, the research team had the parents of each twin fill out nine questions to assess the children impulsivity and nine questions to assess the child’s inattention. Using four possible answers to code: (0) not at all, (1) just a little, (2) pretty much, and (3) very much, parents were asked to complete the form. Then, a one-year retest was performed, using the same questionnaire. In their study, the results indicated that there was a link between environmental influences during early childhood and the lasting effects of ADHD symptoms. Over half of the environmental differences in inattention and hyperactivity disappeared over time, rather than remaining stable (Livingstone et al.). In an effort to further the insight on the nature-nurture question, in 2014, researchers Scaini, Belotti, and Ogliari, examined the relationship between social anxiety disorders and the genetic and environmental influences on individuals of different ages. As the team pointed out, anxiety disorders, specifically social anxiety disorders, are the most common psychiatric illnesses. Social anxiety disorders, or SAD, is characterized by “a marked and persistent fear of one or more social situations in which the person is exposed to unfamiliar people or to possible scrutiny by other, marked fear or anxiety about one or more social situations in which the individual is exposed to possible scrutiny by others” (American Psychiatric Association, 2013). Here, the research team wanted to explore the genetic and environmental contributions to social anxiety disorders.
Studying classic twin studies, the team used a meta-analysis. From the selected papers the team used, 13 cohorts were obtained for a total of 45,585 individuals, regardless of age. However, some parts of the cohorts were examined according to age, which found a more evolutionary influence estimate for social anxiety disorders in children as high as 54%, with the remaining variances being attributed to non-genetic, or environmental factors (Scaini et al.).
As the results indicated, genetic and non-shared environmental factors were substantially consistent of variance in different phenotypes