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9

Monozygotic twin studies are the general course of action for this kind of question. Genetic and environmental influences on multiple dimensions of religiosity: a twin study concludes there is a genetic component. A complete approach for these kind of studies is to take twins that have been separated to different households from birth and compare them to ...


8

Heritability estimates of Extraversion (and other Big 5 factors) The introduction section of Loehlin et al (1998) provides a narrative review of heritability estimates of big 5 personality traits (i.e., one of which is extraversion). A brief extract gives a flavour of some of the research that has been conducted: A recent heritability analysis of the ...


7

To learn about other twins reared apart, investigate the earlier Minnesota Study of Twins Reared Apart and the ongoing Minnesota Twin Family Study. To pique your curiosity: Jim Lewis and Jim Springer stand out in the Minnesota Study of Twins Reared Apart because some of their two histories were strikingly identical; several notable examples: 1st wife: ...


7

There are (at least) two ways epigenetic traits are inherited. The important background in both cases is gene expression: there is a misconception that genes are for this or that, where the reality is that most traits come from an overlap of several genes expressing themselves in different ratios. As a simple example, consider two varieties of bird of the ...


6

Short answer People with above-normal hearing exist. Background Normal hearing was defined as the average of a group of young healthy individuals. These normal hearing levels are currently used to express acoustic sensitivities. One commonly used way is to use decibels relative to this normal hearing level (dB NH). This scale is used in audiograms (Schnupp ...


6

In my mind there are two main explanations of this kind of instinct behaviours. The first one is rooted in evolution. There are many examples of human innate behaviours which we can't explain e.g. when we see a lace or tape on the street we automatically jump and feel scared. Although we live in big city our brain associates the lace with a snake. It is ...


6

First of all, asymmetries in apparently symmetric creatures (of which most are) are actually quite typical. However, in most cases of hand dominance, there is no population-wide hand dominance. In other words, the population is split 50/50 between left and right handers. In humans, however, a lack of hand dominance is often associated with cognitive ...


6

psychological sequelae might be a word you're looking for if you forgive that it's somehow still neurobiological; it is however, not genetic or developmental or something somebody was born with: Chronic kidney disease, for example, is sometimes a sequela of diabetes, and neck pain is a common sequela of whiplash or other trauma to the cervical vertebrae. ...


5

As I alluded in the comments, I think your question is underpinned by a more fundamental worry of the "best level of description" for psychological phenomena. If you a reductionist then you believe that all of psychology is best explained in terms of the activity of neurons (or systems of neurons if you are of the system perspective; note that some do not ...


4

Yes, phobias appear to be partly hereditary. This encompasses both genetic and environmental factors. Kendler et al. (1999) review some work in this area: We have previously reported, from a population-based sample of female twins, that the liability to agoraphobia, social phobia and animal phobia was modestly infuenced by genetic factors with ...


3

Heritability is the proportion of differences in some observable trait (the phenotype; e.g., intelligence, height, love for pizza) in a population that corresponds to differences in the genotype. Heritability is estimated by comparing people who differ in terms of their genetic similarity and the non-genetic influences they are exposed to. For example, we ...


2

In addition to MariaAnt's good contribution, let me take another angle. You wrote: Studies comparing identical and fraternal twins, or occasionally identical twins reared apart have mostly concluded that there is a pretty high heritability of IQ. These studies, in particular the identical twins reared apart studies, imply that someone with the same genes ...


2

There are several ways in which this apparent paradox can be resolved. As a starting point, it is important to consider how heritability is defined and assessed (also see this earlier answer). As you point out, heritability estimates originate from comparisons between people who differ in their genetic similarity (e.g., monozygotic vs. dizygotic twins). The ...


2

The following comes from my research experience using fMRI to study the human visual system. Overall, peoples brains are similar to each other on higher scales, and become very different from each other as the scale becomes smaller. Differences between different people start with brain size and sulci patterns. Also male and female brain anatomies will be ...


2

The Wikipedia article seems to provide a summary of this information with links to the primary literature http://en.wikipedia.org/wiki/Causes_of_schizophrenia#Genetics Concordance rates between monozygotic twins vary in different studies, approximately 50%; whereas dizygotic twins was 17%. Some twin studies (Koskenvuo et al; Hoeffer et al) have ...


2

This is my own conjecture: I would think a Nature/neurobiological/genetic disorder would be classified as some sort of "Structural Disorder." Maybe the Nurture side would be something like "Processing Disorder"? (this is assuming we're talking maladaptive effects) Is our science even to a point where we can differentiate between a neurobiological ...



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