Types of studies
Studies that use the separation of biological and social parentage brought about by adoption to assess the relative importance of genetics and environmental influences.
Adoption studies
The hereditary unit of life in a chromosome. Contains a unique segment of DNA that provides the complete instructions for making a protein or several related proteins that each cell type (e.g., skin, liver) needs to create a unique individual.
Gene
A behavioral disorder that appears to be influenced by genetics. It is characterized by problems with maintaining attention and by impulsivity and hyperactivity.
Attention deficit hyperactivity disorder (ADHD)
A specialized process of cell division that reduces the chromosome number to the single (haploid) complement (n). It takes place in germline cells. It produces four haploid daughter cells from one diploid cell, involving one round of DNA replication.
Meiosis
The study of the relationship between genetics and environment in determining individual differences of behaviour.
Behavioral genetics
A statistical test that evaluates how well a set of observations fit a predicted outcome. The chi-square is often referred to as a “goodness of fit” test.
Chi-square
The study of the patterns of inheritance of specific traits and their variation among organisms.
Genetics
An anxiety disorder characterized by the presence of obsessions or compulsions; having one or both is sufficient for the diagnosis. An obsession is a recurrent or persistent thought that is intrusive or inappropriate. A compulsion is a repetitive behaviour a person feels driven to perform. This behaviour can be a physical action (e.g. hand washing) or a mental act (e.g. praying, repeating words silently, counting.) The behaviour is aimed at neutralizing anxiety or distress.
Obsessive-compulsive disorder (OCD)
The source of genetic variation. A change in the wild type (gene) sequence or in the number or structure of chromosomes that may or may not have observable effect or significant impact on health.
Mutation
An explanation of a fundamental principle that has been so thoroughly tested and supported by multiple lines of evidence that it is accepted by the scientific community.
Theory
An experimental approach that seeks to determine the relative contribution of genetic effects to a trait. It involves comparing the phenotypic similarities between identical twins (which share all their genes) with the phenotypic similarities between fraternal twins (which share half their genes, on average).
Twin studies
The genetic makeup of a cell or organism.
Genotype
A mental illness having a genetic component. It is characterized by onset in early adulthood, deterioration in level of function, and psychotic symptoms, such as auditory and visual hallucinations and paranoia.
Schizophenia
The process of synthesizing a protein molecule. An RNA message (mRNA) directs the order of amino acids being bonded together to form a protein. This process takes place on structures known as ribosomes.
Translation
The controversy over whether genetic inheritance or environment (upbringing) determines behaviour.
Nature vs. Nurture
A tool for detecting genetic influences on behavior. A quantitative trait is measured in animals of mixed genetic background, which produces a continuous distribution of phenotypes. Animals exhibiting high and low extremes for the trait are selected as parents for the next generation. If the trait has a genetic basis, then there will be divergence over time in the value of the trait in offspring selected for high and low values.
Animal selection studies
The view that the development of an organism is determined solely by genetic factors. This view is not supported by scientists.
Genetic determinism
A specific reading disability that is influenced by genetics.
Dyslexia
The process through which an RNA molecule is synthesized by complementary base pairing using DNA as a template. For example, messenger RNA (mRNA) is a product of transcription.
Transcription
A view of human nature derived from Immanuel Kant’s philosophy that maintains that there is interaction between the physical (brain, nervous system, and body) and the mind.
Interactionism
An approach used to test whether a gene influences a trait. Comparisons are made between observations of alleles for a candidate gene in populations of individuals with or without the trait. If a particular allele is observed more often in the group with the trait than in the group without the trait, then that allele may influence the trait.
Association studies
Instructions in a gene that tell the cell how to make specific proteins. Each gene's code combines four nucleotides in various ways to spell "words" that specify which amino acid is needed when making a protein.
Genetic code
A genetic disorder that results from a deficiency of a liver enzyme, phenylalanine hydroxylase. This lack of enzyme activity results in a toxic buildup of phenylalanine metabolites that lead to tissue damage and mental retardation. Newborns diagnosed with PKU can be placed on a special diet, low in phenylalanine, that can prevent the onset of mental retardation.
Phenylketonuria (PKU)
The process of cell division that ensures that each daughter cell receives an exact copy of the diploid (2n) complement of chromosomes.
Mitosis
A concept from philosophy that maintains that all human thought and action is completely determined by physical and biological forces. A consequence of determinism is that freedom and autonomy cease to exist.
Determinism