Sexy son hypothesis - Psychology Wiki
In a well-known study conducted in Denmark with 5000 children of schizophrenic parents who have been adopted or reared away from their parents (Kety et al., 1975) it was found that the biological relatives of schizophrenics were significantly more often schizophrenic than the biological relatives of a control group matched for age, sex and social class. The adopted relatives of the schizophrenics (i.e. the adoptive parents, siblings etc) showed no greater incidence of schizophrenia than the controls.
It has also been found that the MZ twin of a schizophrenic is not only more likely to be schizophrenic but is also more likely to show other forms of psychosis even if not diagnosed with schizophrenia (Heston, 1970).
It is thought likely that a diathesis-stress model best explains schizophrenia. I.e. people have a genetic diathesis or predisposition towards the illness and then environmental factors influence whether the disease is realized.
Bipolar disorder (previously manic-depression): characterised by severe depressions, alternating with hyperactive, frenetic, talkative behaviour, grandiose thoughts, a rush of ideas (mod may be elevated but can also be highly agitated).
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Schizophrenia is characterized by disorientation, confusion, cognitive disturbance, separation from reality. Many studies have shown a genetic susceptibility to schizophrenia exists. For example, it has been shown that in general, parents brothers and sisters of schizophrenics are more likely to suffer from schizophrenia than those not so related. In fact, the more closely one is related to a schizophrenic, the greater the likelihood of having schizophrenia.
We�ll now turn our attention to a brief look at the likelihood of a genetic component to a couple of diffferent pathological conditions: schizophrenia and bipolar disorder.
Testing the sexy son hypothesis—a research framework …
Rushton, Fulker, Neale, Nias and Eysenck, (1986) found aggressiveness partially hereditary. They assessed 500+ MZ and DZ twin pairs on altruism, empathy, nurturance, assertiveness and aggressiveness and found high correlations for MZ twins for each personality variable.
The ‘sexy sons’ hypothesis - Body Language Journal
Humans are highly similar to each other genetically. About 90% of human genes are identical from one individual to another. Behavioural genetics concentrates on the approximately 10% of the human genome that does vary.
Behavioural genetics, like trait psychology, focuses exclusively on aspects of personality that differ from one individual to another. The inheritance of species-specific traits or traits that all humans share is examined later in evolutionary psychology.
The basic assumption of behavioural genetics is that if a trait is influenced by genes then it ought to be more highly correlated across pairs of identical (monozygotic:MZ) twins than across pairs of fraternal (dyzygotic:DZ) twins, and more highly correlated across closer genetic relatives than across more distant genetic relatives.
Across many personality traits the average correlation across MZ twins is .50 and across DZ twins is .30 (e.g. Bouchard & McGue, 1990; Loehlin & Nichols, 1976). Thus according to twin studies average heritability of most personality traits is .40. This is interpreted to mean that the proportion of behavioural variance that can be explained by genetic variance is 40%. (This is a heritability coefficient i.e. a percentage not a correlation coefficient).
Sexy son hypothesis | Wiki | Everipedia
The basic methodology of behavioural genetics is to compare similarities in personality between individuals who are and are not genetically related, or who are related to different degrees.
The ‘Sexy Sons’ Hypothesis: Why Women Have Better …
During human history, it seems males evolved with particular tendencies and capacities that were advantageous for hunting and physical defence of tribes. This underlying predisposition of males seems to also predispose males to also being more likely to have overly violent behaviors. This may be due to higher than normal levels, for example, of particular hormones and neurochemicals (testosterone, for example). Other behavioral sex differences which have attracted evolutionary explanations include the higher rates of promiscuity for males, and the higher rates of rape by males.