Such examples of phenotypic variability in inbred mice have always been attributed to environmental influences that are difficult to control and measure, such as variations in prenatal and postnatal development and early dominance hierarchies ([Peaston and Whitelaw, 2006] and [Wong et al., 2005]). However, experiments performed on inbred mice raised in strictly defined environments have shown that up to 80% of random variability in quantitative traits (e.g., body weight) are unrelated to genetic and environmental influences (Gartner, 1990). This third component to natural variation is thought to maintain Gaussian distributions of biological variables independent of environmental influences and sequence constraints and is now attributed to chromatin remodeling events such as histone acetylation or methylation.

We show here that while Val/Val and Met/Met mice showed comparable behavior on baseline measures of emotionality, Met/Met mice displayed a striking Unsusceptible [to depression following social defeat] phenotype in the social defeat paradigm, which was associated with a ~50% reduction in levels of BDNF protein

Asymptomatic brain infarcts were present in 145 persons (7.2%). Among findings other than infarcts, cerebral aneurysms (1.8%) and benign primary tumors (1.6%), mainly meningiomas, were the most frequent. The prevalence of asymptomatic brain infarcts and meningiomas increased with age, as did the volume of white-matter lesions, whereas aneurysms showed no age-related increase in prevalence.

Fig. 1 shows that children with a meningitis severity score above the median had a 6.2 times higher risk of becoming lefthanded at school age compared to those below the median (95% CI 2.0--18.6). Furthermore, those who contracted meningitis below the median age of 1.8 years had a 12.3 times higher risk (95% CI 2.6--58.0) compared to a 5.9 times higher risk (95% CI 1.6--21.7) among children who contracted meningitis at older age.
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More specific analyses on cognitive function are shown in Table 3, with left-handed children generally performing worse on the cognitive tests. Left-handed children had an almost seven points lower IQ (p = 0.018), a one point lower vocabulary score of WISC-r (p = 0.061), and an almost five points lower Beery score (p = 0.069) than their non-left-handed counterparts.

Although the effects were small, it should be noted that a 5% difference means about a 30% change in NRH (e.g. 15.7% in pedophiles vs. 11.5% in controls).
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In contrast, education is not related to the handedness/pedophilia relationship. Pedophiles had elevated NRH relative to controls with or without controlling for education. This result suggests that, even though pedophiles have a rate of NRH comparable to other offenders (or perhaps slightly higher), there may be a different mechanism underlying the handedness/pedophile relationship than the handedness/(general) criminality relationship. Thus, elevated NRH in pedophiles probably does not merely represent a 'criminal/antisocial behavior' tendency, because of, for example, general cognitive and/or educational difficulties. Instead, these data may indicate that elevated NRH in pedophiles reflects [Central Nervous System] abnormalities that, in part, directly affects their sexual preference systems (see [24] for a review of CNS abnormalities in pedophiles).

The group differences did not change appreciably after the addition of the covariates [i.e., Age and Wechsler Full Scale IQ; agnostic], F(2, 294) = 6.31, eta^2 = .041, p = .002, and simple effects contrasts showed that both the pedophilia group and the hebephilia group reported significantly less right-handedness than did the teleiophilia group, t(294) = -3.51, eta^2 = .040, p = .001 (twotailed), and t(294) = -2.14, eta^2 = .015, p = .033 (two-tailed), respectively.

The results indicated that, in general, measures of cognitive ability correlated negatively with sexual response to children and positively with sexual response to adults. Handedness, however, was significantly related to phallometric response to children, only. [From Table 4, partial correlation of arousal by prepubescent stimuli and handedness = -.13, p less than .05, where negative handedness indicates left-handedness; agnostic.] There was little evidence of association between the neuropsychological variables and sexual response to stimuli depicting pubescents in the laboratory.