Chapter 3 - Origins of criminal behavior: biological factors Flashcards
Aggression and biological/social factors
- Early onset aggressive tendencies: often exhibit biological and neurological abnormalities or deficits
- Late-onset offending appears to be more influenced by social factors
- This leads criminologists to agree that while genetics and biological factors do play a role, social environment is the most important determinant of criminal behavior.
Biopsychologists
psychologists who study the biological aspects of criminal behavior.
Behavior genetics
- focuses on examining the role that genes play in the formation and development of human and animal behavior
- branch of biology that investigates the relationship between genes and the environment in determining individual differences in behavior.
- some methods are used to disentangle genetic from environment influences in twin and adoption studies
Molecular genetics
- field of biology that studies the structure and function of genes at the molecular level.
- focuses on specific genes as foundations for certain patterns of behavior.
- how genes are transferred from generation to generation
Traditional behavior genetic viewpoints
Views behavioral differences as springing from 3 genetic/environmental sources:
1) Influences attributable to genetic effects
2) environmental influences shared by siblings (family/environments)
3) influences that arise from unshared environmental experiences that make siblings differ from one another
Dizygotic (DZ) twins
- also fraternal twins
- develop from two different fertilized eggs
- no more genetically alike than nontwin siblings
- equally susceptible to prenatal environmental influences such as nicotine, alcohol, etc.
Monozygotic (MZ) twins
- also identical twins
- develop from single egg
- always same sex, share 100% of same genes
Monochorionic
MZ twins who share the same chorion, the outer membrane that encloses the embryo, approx. 2/3 of MZ twins are this way. Studies show that MZ, monochorionic twins are more similar in personality and cognitive ability than dichorionic, MZ twins
Dichorionic
MZ twins who have different chorions in utero, approx. 1/3 of MZ twins are this way. As a result they have slightly different prenatal environments, although the difference IS small.
Shared environments
Sometimes referred to as common environments, include prenatal and life experiences affecting both twins in the same way
Nonshared environments
Include living experiences that are different for each twin, such as being raised in a different home environment, participating in different activities, or attending different schools. Research shows nonshared environments account for approx. 30% of the variation in antisocial behavior, although developmental factors of course play a role.
Concordance
A key term in twin research, this is the term used in genetics to describe the degree to which related pairs of subjects both show a particular behavior or condition, and is usually expressed in percentages.
(TEDS) Twins’ Early Development Study
- ongoing, based at King’s College London under Professor Robert Plomin
- explores behavior problems as well as problematic development in language, cognition, and academic abilities from early childhood through adolescence.
Family influences vs. Genetic influences
- studies seem to show that family influences (i.e. positive parenting experiences and familial guidance) have an influence on a child’s aggressive tendencies, BUT the genetic predispositions and factors play an increasing role as the individual grows older, and familial influences play a smaller and smaller role as adolescence and adulthood sets in.
MAOA-L gene
nicknamed “the warrior gene” by some researchers, low activity from this gene has been linked to aggression and violence, and is carried by an estimated 1/3 of the population. Studies show that people with this gene who were also exposed to adverse childhood experiences were more likely to be offenders in late adolescence and adulthood.