Chapter 2 - Behavioral Genetics Flashcards
Chromosomes
23 pairs of chromosomes
46 total chromosomes
(First 22 are autosomes, last one is our sex chromosome)
All children have an X chromosome
Sperm provides either an X or Y
Each chromosome consists of DNA
Gene
Provides a specific def of biochemical instructions
The majority of genes are all the same in all people
Less than 1% of genes cause the differences we see in ppl
Genotype
The complete set of genes making a persons hereditary (genetic make up)
Phenotype
An individuals physical, behavioral, and psychological features
(created by both genetic features and environmental influences)
Environment can influence how certain genes are expressed
Alleles
Different versions of a gene
Homozygous
When alleles in a pair of chromosomes are the same (BB;bb)
Heterozygous
When alleles in a pair of chromosomes are different (Bb)
Dominant Allele (B)
Chemical instructions are typically followed
Recessive Allele (b)
When paired with a dominant allele instructions ignored
Incomplete dominance
Sometimes one allele does not dominate the other completely—the phenotype that results fall between dominant and recessive
(Example: dominant trait= curly hair + recessive trait= straight hair = incomplete dominance= wavy hair)
Genetic disorder
Genetics can harm development in two ways:
Inherited disorders
Abnormal number of chromosomes
Inherited disorders
A genetic problem caused by abnormalities in genome (rare and typical caused by the presence of two recessive alleles)
Note: most genetic disorders are not caused by dominant alleles
Abnormal number of chromosomes
When children are born with missing, extra, or damaged chromosomes developmental disruptions occur
(More common than inherited disorders)
Single-gene inheritance
Phenotypes that rely on the make up of a single gene
Polygenetic Inheritance
Phenotypes that reflect the combined activity of many separate genes
(Example: eye color, skin color)
Genotype to phenotype
Genotype leads to a phenotype but only if the environment cooperated in the usual manner
(Some genotypes only lead to phenotype if certain environment is present)
Epigenesis
Continuous interplay between genes and multiple levels of the environment (from cells subculture) driving development
Niche-picking
Deliberately seeking out environments that fit ones heredity
Heritability coefficient
Estimates the extent to which differences between people reflect heritability
(Heritability coefficients apply to groups in certain environments not individuals)
Behavioral genetics
Determining the impact of heredity on behavioral and psychological traits
Methods of behavioral genetics: twin studies, adoption studies
Genetic inheritance is never the sole determinant of behavioral development – always need to consider role of the environment
Twin studies
Strong genetic influence is seen when identical twins look more similar than fraternal twins
Limitations: do people treat identical twins more similarly then fraternal twins
Monozygotic Twins
Identical twins come from a single fertilized egg that splits in two (share the same genetic make up for body structure, height, and facial features)
Dizygotic Twins
Fraternal twins come from two separate fertilized eggs (by separate sperm)
Share about half of their genes
Adoption studies
Adopted children can be compared to: biological parents because of genes and adopted parents because of influence of environment
Limitations: often adoption agencies place children with a family similar to their biological family, If adoptive and biological parents are similar it becomes too difficult to assess environment and genetic influence
