Behavioural genetics is the field of biology that studies the role of genetics in animal (including human) behaviour. The field is an overlap of genetics, ethology and psychology. Classically, behavioural geneticists have studied the heritability of behavioural traits. This article needs additional references or sources for verification. ... DNA, the molecular basis for inheritance. ... For other uses, see Animal (disambiguation). ... Behavior or behaviour refers to the actions or reactions of an object or organism, usually in relation to the environment. ... DNA, the molecular basis for inheritance. ... This article or section does not adequately cite its references or sources. ... Psychology (from Greek: ψυχή, psukhē, spirit, soul; and λόγος, logos, knowledge) is both an academic and applied discipline involving the scientific study of mental processes and behavior. ... Heritability, as used professionally in genetics, has a very precise definition. ...

Francis Galton

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History

In 1869, Francis Galton published the first empirical work in human behavioural genetics, Hereditary Genius. Here, Galton intended to demonstrate that "a man's natural abilities are derived by inheritance, under exactly the same limitations as are the form and physical features of the whole organic world." Like most seminal work, he overstated his conclusions. His was a family study on the inheritance of giftedness and talent. Galton was aware that resemblance among familial relatives can be a function of both shared genes and shared environments. Contemporary behavioural genetics studies special populations—in human research, twins and adoptees and in animal research, specially bred strains and lines—to separate genetic from environmental effects. This article does not cite any references or sources. ... The subject of the inheritance of intelligence is the genetics of mental abilities. ... A twin study is a kind of genetic study done to determine heritability. ...

The initial impetus behind behavioural genetic research was to demonstrate that there were indeed genetic influences on behaviour. In psychology, this phase lasted for the first half of the 20th century largely because of the overwhelming influence of behaviourism in the field. Later behavioural genetic research focused on quantitative methods, and today there is a large emphasis on applying techniques from molecular genetics to isolate individual genes that influence behaviour. Behaviorism (or behaviourism) is an approach to psychology based on the proposition that behavior is interesting and worthy of scientific research. ... Molecular genetics is the field of biology which studies the structure and function of genes at a molecular level. ...

Contemporary behavioural genetics

Currently, the largest branch of behavioural genetics is psychiatric genetics which studies phenotypes such as schizophrenia, bipolar disorder, and alcoholism. Psychiatric genetics is a relatively recent subfield of behavioral genetics, which studies the role of genetics in various psychological impairments such as alcoholism, schizophrenia, bipolar disorder and neurodevelopmental disorders such as those of the autistic spectrum. ... For other uses, see Bipolar. ... Alcoholism is the consumption of, or preoccupation with, alcoholic beverages to the extent that this behavior interferes with the drinkers normal personal, family, social, or work life, and may lead to physical or mental harm. ...

Recent trends in behaviour genetics has indicated an additional focus toward researching the heritability of human characteristics typically studied in developmental psychology. For instance, a major focus in developmental psychology has been to characterize the influence of parenting styles of children. However, in most studies, genes are a confounding variable. Because children share 50% of their genes with each parent, any observed effects of parenting styles could be effects of having many of the same genes as a parent (e.g. harsh aggressive parenting styles have been found to correlate with similar aggressive child characteristics- is it the parenting or the genes?). Thus, behaviour genetics research is currently undertaking to distinguish the effects of the family environment from the effects of genes. This branch of behaviour genetics research is becoming more closely associated with mainstream developmental psychology and the sub-field of developmental psychopathology as it shifts its focus to the heritability of such factors as emotional self-control, attachment, social functioning, aggressiveness etc.. This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... Parenting style is a psychological construct representing standard strategies parents use in raising their children. ... This article includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... There are very few or no other articles that link to this one. ...

Several academic bodies exist to support behavior genetic research, including the International Behavioural and Neural Genetics Society, Behavior Genetics Association and the International Society for Twin Studies.Behavior genetic work features prominently in several more general societies, for instance the International Society for Psychiatric Genetics and the International Behavioral Neuroscience Society. IBANGS, the International Behavioural and Neural Genetics Society, was founded in 1996 as the European Behavioural and Neural Genetics Society. ... The Behavior Genetics Association is a group that promotes research into the connection between heredity and behavior. ...

Methods of behavioural genetics

Behavioural geneticists use several designs to answer questions about the nature and mechanisms of genetic influences on behavior. All of these designs are unified by being based around human relationships which disentangle genetic and environmental relatedness.

So, for instance, some researchers study adopted twins: the adoption study. In this case the adoption disentangles the genetic relatedness of the twins (either 50% or 100%) from their family environments. Likewise the classic twin study contrasts the differences between identical twins and fraternal twins within a family compared to differences observed between families. This core design can be extended: the so-called "extended twin study" which adds additional family members, increasing power and allowing new genetic and environmental relationships to be studied. Excellent examples of this model are the Virginia 20,000, and the QIMR twin studies. A twin study is a kind of genetic study done to determine heritability. ...

Also possible are the "children of twins" design (holding maternal genetic contribution equal across children with paternal genetics and family environments; and the "virtual twins" design - unrelated children adopted into a family who are very close or identical in age to biological children or other adopted children in the family.

Criticism

Many scientists from multiple disciplines including Statistical Genetics, Statistics and Psychology question the validity of twin study research and maintain that conclusions reached via this method are ambiguous in nature or may actually be meaningless, altogether. It has been shown that the Statistical underpinnings and sampling that these studies base themselves are of questionable value. Statistical critics maintain that heritability estimates used for most twin studies rest on restrictive assumptions which are usually not tested, and if they are, are often found to be violated by the data. For example, Peter Schonemann, a noted statistician and Psychometrics expert has shown that Heritability estimates often produce unusually high results for things that have nothing to do with genes. For example, The narrow heritability’s of HR of responses to the question “did you have your back rubbed” has been shown to work out to .92 heritable for males and .21 heritable for females. While using the statistical models published in Loehlin and Nichols (1976) the question “Did you wear sunglasses after dark?” is 130% heritable for males and 103% for females. ^[1][2] For a List of scientists, see: List of anthropologists List of astronomers List of biologists List of chemists List of computer scientists List of economists List of engineers List of geologists List of inventors List of mathematicians List of meteorologists List of physicists Scientist pairs List of scientist pairs See... DNA, the molecular basis for inheritance. ... Psychology (from Greek: ψυχή, psukhÄ“, spirit, soul; and λόγος, logos, knowledge) is both an academic and applied discipline involving the scientific study of mental processes and behavior. ... For Wikipedia statistics, see m:Statistics Statistics is the science and practice of developing human knowledge through the use of empirical data expressed in quantitative form. ... Sampling may refer to: Sampling (signal processing), converting a continuous signal into a discrete signal Sampling (music), re-using portions of sound recordings in a piece Sampling (statistics), selection of observations to acquire some knowledge of a statistical population Sampling (case studies), selection of cases for single or multiple case... A critic (derived from the ancient Greek word krites meaning a judge) is a person who offers a value judgement or an interpretation. ... Heritability, as used professionally in genetics, has a very precise definition. ... Look up Study in Wiktionary, the free dictionary To study means to acquire knowledge, often by memorization or reading. ... Peter H. Schönemann is a German born psychometrician and statistical expert. ... Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, and personality traits. ... Heritability, as used professionally in genetics, has a very precise definition. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ...

The theory of correlation between relatives has been of vast importance in plant and animal breeding because it is possible to design and carry out experiments to estimate variance components in expressions for covariances between relatives. However, data on humans is observational and individuals are not randomly assigned to environments, so that estimation of heritability from such data is not on the same firm foundation as it is in plant and animal breeding contexts ^[3]Heritability estimates themselves are inaccurate, given the potential for gene-environment covariance and interaction, as well as other non-additive effects on behavior. The revolution in molecular genetics' has provided more effective tools for describing the genome, but doesn't permit separation of gene and environmental effects on traits. ^[4] The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion. ... Positive linear correlations between 1000 pairs of numbers. ... Kinship is the most basic principle of organizing individuals into social groups, roles, and categories. ... For other uses, see Plant (disambiguation). ... Selective breeding in domesticated animals is the process of developing a cultivated breed over time. ... In probability theory and statistics, the variance of a random variable (or somewhat more precisely, of a probability distribution) is a measure of its statistical dispersion, indicating how its possible values are spread around the expected value. ... Heritability, as used professionally in genetics, has a very precise definition. ... For other uses, see Plant (disambiguation). ... Selective breeding in domesticated animals is the process of developing a cultivated breed over time. ...

Other critics’ note that in human populations twins are not a random sample of the population - They are not even a representative sample^{[5] [6]}. For example: Dizygotic (DZ) twin births are affected by many factors. Some women frequently produce more than one egg at each menstrual period and, therefore, are more likely to have twins. This tendency may run in the family either in the mother's or father's side of the family, and often runs through both. Women over the age of 35 are more likely to produce two eggs. Women who have three or more children are also likely to have dizygotic twins. Artificial induction of ovulation and in vitro fertilization-embryo replacement can also give rise to DZ and MZ twins ^{[7] [8] [9][10][11] [12]} To study the effect of some environmental factors, an experimenter will need to bring up a random sample of genotypes in different environments. Similarly, to study the effect of the same environment on genotypes, one would need to bring up individuals of the same genetical composition in that environment.^[13][14][15] Fraternal twin boys in the tub The term twin most notably refers to two individuals (or one of two individuals) who have shared the same uterus (womb) and usually, but not necessarily, born on the same day. ... Look up egg in Wiktionary, the free dictionary. ... The menstrual cycle is the periodic change in a womans body that occurs every month between puberty and menopause and that relates to reproduction. ... a family of Ouagadougou, Burkina Faso in 1997 Family is a Western term used to denote a domestic group of people, or a number of domestic groups linked through descent (demonstrated or stipulated) from a common ancestor, marriage or adoption. ... Look up artificial in Wiktionary, the free dictionary. ... Look up induction in Wiktionary, the free dictionary. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ... ... Categories: Biology stubs ... For other uses, see Embryo (disambiguation). ... An environment is a complex of external factors that acts on a system and determines its course and form of existence. ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ... The genotype is the specific genetic makeup (the specific genome) of an individual, usually in the form of DNA. It codes for the phenotype of that individual. ... This article is about the general scientific term. ...

References

• Carey, G. (2003) Human Genetics for the Social Sciences. Thousand Oaks, CA: Sage Publications. [1]
• DeFries, J. C., McGuffin, P., McClearn, G. E., Plomin, R. (2000) Behavioral Genetics 4th ED. W H Freeman & Co.
• Scott, J.P. and Fuller, J.L. (1965) Genetics and the Social Behavior of the Dog. University of Chicago Press.
• Weiner, J. (1999) Time, Love, Memory : A Great Biologist and His Quest for the Origins of Behavior. Knopf

Robert Plomin is an American psychologist best known for his work in twin studies and behavior genetics. ... Jonathan Weiner is a Pulitzer Winning author of non-fiction books on his biology observations, in particular evolution in the Galápagos Islands, genetics, and the environment. ...

External links

• US Human Genome Project on Behavioral Genetics