Genes make an important contribution to individual personality differences
The best studied aspects of personality in relation to behavioral genetics are the factors extraversion (sociability, impulsivity) and neuroticism (emotional variation, anxiety, irritability). In general, in twin studies, personality variables have a moderate genetic influence (of the order of 50% or smaller), while the rest of the variations depend on the non-shared environment and only a small percentage of the variance has to do with the shared environment.
Regarding the evolution of personality characteristics, the results are inconclusive. While in the case of the intelligence There is an increase in the weight of genetic factors as age progresses, this has not been clearly demonstrated in the case of personality. However, it has been found that, in any case, if the effect of genes changes throughout the development of personality characteristics, this change also tends to go in the direction of increasing their importance.
Regarding personality and other behaviors or attitudes (for example, the degree of religiosity, conservatism or position regarding the death penalty), genes do not determine or create them, but rather affect the selection of options offered to us. the environment.
There are currently some specific candidate genes to modulate certain personality characteristics, such as aggressiveness. The gene most clearly associated with a personality factor, the search for novelties, is the one located on chromosome 11 that codes for the receptor of the dopamine DRD4, which is expressed especially in the nucleus accumbens. The gene contains a variable repeating fragment of 48 base pairs (called a mini-satellite). This sequence can be repeated two to eight times. It has been found that subjects who are carriers of long repetition alleles score higher in the search items for novelties in personality questionnaires.
Regarding the personality disorders, the most studied from a genetic point of view have been schizotypal disorder, obsessive-compulsive personality disorder and especially antisocial personality disorder. In the case of schizotypal disorder, it has been observed that it occurs to a greater extent in family groups. There is a higher proportion of people with this disorder among first-degree relatives. Obsessive-compulsive personality disorder also presents a certain degree of heritability and is etiologically associated with anxiety disorders.
Antisocial personality disorder is characterized by a history of antisocial behaviors that begin during adolescence and continue into adulthood. The presence of a family group in antisocial personality disorder has been observed, and studies of twins and adoptions indicate that there is a remarkable influence of genetic factors, especially among boys. Similarly with what happens in the case of intellectual cogent, the heritability of antisocial disorder increases from adolescence to adulthood. Similarly and to some extent parallel to the antisocial personality disorder and criminal behavior also has more genetic influence in adulthood than before the age of fifteen, in which the shared environment makes an important contribution.
Bradford, H.F. (1988). Fundamentals of neurochemistry. Barcelona: Labor.
Carlson, N.R. (1999). Behavioral physiology. Barcelona: Ariel Psychology.
Carpenter, M.B. (1994). Neuroanatomy Fundamentals Buenos Aires: Panamerican Editorial.
Delgado, J.M .; Ferrús, A .; Mora, F .; Blonde, F.J. (eds) (1998). Neuroscience Manual. Madrid: Synthesis.
Diamond, M.C .; Scheibel, A.B. and Elson, L.M. (nineteen ninety six). The human brain Work book. Barcelona: Ariel.
Guyton, A.C. (1994) Anatomy and physiology of the nervous system. Basic Neuroscience Madrid: Pan American Medical Editorial.
Kandel, E.R .; Shwartz, J.H. and Jessell, T.M. (eds) (1997) Neuroscience and Behavior. Madrid: Prentice Hall.
Martin, J.H. (1998) Neuroanatomy. Madrid: Prentice Hall.
Nolte, J. (1994) The human brain: introduction to functional anatomy. Madrid: Mosby-Doyma.