Related Research Articles
Adoption is a process whereby a person assumes the parenting of another, usually a child, from that person's biological or legal parent or parents. Legal adoptions permanently transfer all rights and responsibilities, along with filiation, from the biological parents to the adoptive parents.
Nature versus nurture is a long-standing debate in biology and society about the relative influence on human beings of their genetic inheritance (nature) and the environmental conditions of their development (nurture). The alliterative expression "nature and nurture" in English has been in use since at least the Elizabethan period and goes back to medieval French. The complementary combination of the two concepts is an ancient concept. Nature is what people think of as pre-wiring and is influenced by genetic inheritance and other biological factors. Nurture is generally taken as the influence of external factors after conception e.g. the product of exposure, experience and learning on an individual.
Twin studies are studies conducted on identical or fraternal twins. They aim to reveal the importance of environmental and genetic influences for traits, phenotypes, and disorders. Twin research is considered a key tool in behavioral genetics and in related fields, from biology to psychology. Twin studies are part of the broader methodology used in behavior genetics, which uses all data that are genetically informative – siblings studies, adoption studies, pedigree, etc. These studies have been used to track traits ranging from personal behavior to the presentation of severe mental illnesses such as schizophrenia.
Human behaviour genetics is an interdisciplinary subfield of behaviour genetics that studies the role of genetic and environmental influences on human behaviour. Classically, human behavioural geneticists have studied the inheritance of behavioural traits. The field was originally focused on determining the importance of genetic influences on human behaviour. It has evolved to address more complex questions such as: how important are genetic and/or environmental influences on various human behavioural traits; to what extent do the same genetic and/or environmental influences impact the overlap between human behavioural traits; how do genetic and/or environmental influences on behaviour change across development; and what environmental factors moderate the importance of genetic effects on human behaviour. The field is interdisciplinary, and draws from genetics, psychology, and statistics. Most recently, the field has moved into the area of statistical genetics, with many behavioural geneticists also involved in efforts to identify the specific genes involved in human behaviour, and to understand how the effects associated with these genes changes across time, and in conjunction with the environment.
Adopted child syndrome is a term that has been used to explain behaviors in adopted children that are claimed to be related to their adoptive status. Specifically, these include problems in bonding, attachment disorders, lying, stealing, defiance of authority, and acts of violence. The term has never achieved acceptance in the professional community. The term is not found in the American Psychiatric Association's Diagnostic and Statistical Manual, 4th edition, TR.
Closed adoption is a process by which an infant is adopted by another family, and the record of the biological parent(s) is kept sealed. Often, the biological father is not recorded—even on the original birth certificate. An adoption of an older child who already knows their biological parent(s) cannot be made closed or secret. This used to be the most traditional and popular type of adoption, peaking in the decades of the post-World War II Baby Scoop Era. It still exists today, but it exists alongside the practice of open adoption. The sealed records effectively prevent the adoptee and the biological parents from finding, or even knowing anything about each other. However, the emergence of non-profit organizations and private companies to assist individuals with their sealed records has been effective in helping people who want to connect with biological relatives to do so.
Thomas J. Bouchard Jr. is an American psychologist known for his behavioral genetics studies of twins raised apart. He is professor emeritus of psychology and director of the Minnesota Center for Twin and Adoption Research at the University of Minnesota. Bouchard received his PhD from the University of California, Berkeley, in 1966.
Lee Willerman was an American psychologist known for his work on behavioral genetics using twin studies.
John Clinton Loehlin was an American behaviorial geneticist, computer scientist, and psychologist. Loehlin served as president of the Behavior Genetics Association and of the Society of Multivariate Experimental Psychology. He was an ISIR lifetime achievement awardee.
The Minnesota Transracial Adoption Study examined the IQ test scores of 130 black or interracial children adopted by advantaged white families. The aim of the study was to determine the contribution of environmental and genetic factors to the poor performance of black children on IQ tests as compared to white children. The initial study was published in 1976 by Sandra Scarr and Richard A. Weinberg. A follow-up study was published in 1992 by Richard Weinberg, Sandra Scarr and Irwin D. Waldman. Another related study investigating social adjustment in a subsample of the adopted black children was published in 1996. The 1992 follow-up study found that "social environment maintains a dominant role in determining the average IQ level of black and interracial children and that both social and genetic variables contribute to individual variations among them."
Sandra Wood Scarr was an American psychologist and writer. She was the first female full professor in psychology in the history of Yale University. She established core resources for the study of development, including the Minnesota Transracial Adoption Study and the Minnesota Adolescent Adoption Study. She served as president of multiple societies including the Association for Psychological Science and was honored with multiple awards including the James McKeen Cattell Fellow Award. She was also active in the development of commercial childcare. Her work with twins in the 1960s revealed strong genetic influences on intellectual development. One of her key findings was that this differed with race and socioeconomic status (SES), with poor and non-white children showing less genetic influence on their IQ and more environmental influence. She demonstrated a successful intervention in premature infants, showing that stimulation improved their health and developmental outcomes.
Interracial adoption refers to the act of placing a child of one racial or ethnic group with adoptive parents of another racial or ethnic group.
The Minnesota / Texas Adoption Research Project (MTARP) is a longitudinal research study that focuses on the consequences of variations in openness in adoption arrangements for all members of the adoptive kinship network: birthmothers, adoptive parents, and adopted children, and for the relationships within these family systems.
Research on the heritability of IQ inquires into the degree of variation in IQ within a population that is due to genetic variation between individuals in that population. There has been significant controversy in the academic community about the heritability of IQ since research on the issue began in the late nineteenth century. Intelligence in the normal range is a polygenic trait, meaning that it is influenced by more than one gene, and in the case of intelligence at least 500 genes. Further, explaining the similarity in IQ of closely related persons requires careful study because environmental factors may be correlated with genetic factors.
Genealogical bewilderment is a term referring to potential identity problems that could be experienced by a child who was either fostered, adopted, or conceived via an assisted reproductive technology procedure such as surrogacy or gamete donation.
Behavioural genetics, also referred to as behaviour genetics, is a field of scientific research that uses genetic methods to investigate the nature and origins of individual differences in behaviour. While the name "behavioural genetics" connotes a focus on genetic influences, the field broadly investigates the extent to which genetic and environmental factors influence individual differences, and the development of research designs that can remove the confounding of genes and environment. Behavioural genetics was founded as a scientific discipline by Francis Galton in the late 19th century, only to be discredited through association with eugenics movements before and during World War II. In the latter half of the 20th century, the field saw renewed prominence with research on inheritance of behaviour and mental illness in humans, as well as research on genetically informative model organisms through selective breeding and crosses. In the late 20th and early 21st centuries, technological advances in molecular genetics made it possible to measure and modify the genome directly. This led to major advances in model organism research and in human studies, leading to new scientific discoveries.
The following outline is provided as an overview of and topical guide to human intelligence:
Research into relative outcomes of parenting by biological and adoptive parents has produced a variety of results. When socioeconomic differences between two-biological-parent and two-adoptive-parent households are controlled for, the two types of families tend to invest a similar amount of resources. A 20-year longitudinal study of 245 adoptees placed in the first few months of life that compared the children's cognitive abilities with those of their birth and adoptive parents found that before age 5, the adoptees' cognitive skills correlated more with those in their adoptive families, but as the adoptees matured, their cognitive skills, including verbal ability, became more like those of their biological parents; thus, the study concluded that "environmental transmission from parent to offspring has little effect on later cognitive ability." Adopted siblings have, on average, an IQ score 4.4 points higher than the siblings who are reared by their biological parents and 3.18 point increase for half-siblings reared by their biological parents.
Adoption studies typically compare pairs of persons, e.g., adopted child and adoptive mother or adopted child and biological mother, to assess genetic and environmental influences on behavior. These studies are one of the classic research methods of behavioral genetics. The method is used alongside twin studies to identify the roles of genetics and environmental variables that impact intelligence, and behavioral disorders.
In adoption studies, selective placement refers to the practice by which adoption agencies tend to deliberately match certain characteristics of an adopted child's adopted parents with those of his or her biological parents. When this occurs, it results in a correlation between environments between biological relatives raised in different homes. It has the potential to bias the conclusions of such studies, because twins who were reared in separate environments may in fact have been reared in much more similar environments than assumed. This can result in an inflated estimate of heritability. There is evidence that selective placement was a major confound in many early studies of twins reared apart. Some adoption studies report little or no evidence of selective placement. For example, a 1979 study by Ho et al. reported a generally low level of selective placement in adopted children for either physical or behavioral traits. The authors concluded that to the extent that selective placement occurred for such traits, "our data suggest that it is based largely on characteristics of the birth father," rather than those of the adoptee. Carey (2003) concluded that selective placement was "moderate" for physical characteristics and typically "small or nonexistent" for behavioral characteristics.
References
- ↑ Horn, J. M. (1983). The Texas Adoption Project: Adopted children and their intellectual resemblance to biological and adoptive parents. Child Development, 54, 268-275.
- ↑ Gottfredson, Linda (December 13, 1994). Mainstream Science on Intelligence. Wall Street Journal , p A18.
