Why are some people more jealous than others? Genetic and environmental factors

Research on romantic jealousy has traditionally focused on sex differences. We investigated why individuals vary in romantic jealousy, even within the sexes, using a genetically informed design of ~7700 Finnish twins and their siblings. First, we estimated genetic, shared environmental and nonshared environmental influences on jealousy, Second, we examined relations between jealousy and several variables that have been hypothesized to relate to jealousy because they increase the risk (e.g., mate-value discrepancy) or costs (e.g., restricted sociosexuality) of infidelity. Jealousy was 29% heritable, and non-shared environmental influences explained the remaining variance. The magnitude and sources of genetic influences did not differ between the sexes. Jealousy was associated with: having a lower mate value relative to one's partner; having less trust in one's current partner; having been cheated by a previous or current partner; and having more restricted sociosexual attitude and desire. Within monozygotic twin pairs, the twin with more restricted sociosexual desire and less trust in their partner than his or her co-twin experienced significantly more jealousy, showing that these associations were not merely due to the same genes or family environment giving rise to both sociosexual desire or trust and jealousy. The association between sociosexual attitude and jealousy was predominantly explained by genetic factors (74%), whereas all other associations with jealousy were mostly influenced by nonshared environmental (non-familial) factors (estimates >71%). Overall, our findings provide some of the most robust support to date on the importance of variables predicted by mate-guarding accounts to explain why people vary in jealousy

Why Is an Early Start of Training Related to Musical Skills in Adulthood? A Genetically Informative Study

Experts in domains such as music or sports often start training early. It has been suggested that this may reflect a sensitive period in childhood for skill acquisition. However, it could be that familial factors (e.g., genetics) contribute to the association. Here, we examined the effect of age of onset of musical training on musical aptitude and achievement in professional musicians (n = 310) and twins (n = 7,786). In line with previous literature, results showed that an earlier age of onset was associated with higher aptitude and achievement in both samples. After we adjusted for lifetime practice hours, age of onset was associated only with aptitude (p .14). Twin analyses showed that the association with aptitude was fully explained by familial factors. Thus, these findings provide little support for a sensitive period for music but highlight that familiar factors play an important role for associations between age of onset of training and skills in adulthood

The effects of playing music on mental health outcomes

The association between active musical engagement (as leisure activity or professionally) and mental health is still unclear, with earlier studies reporting contrasting findings. Here we tested whether musical engagement predicts (1) a diagnosis of depression, anxiety, schizophrenia, bipolar or stress-related disorders based on nationwide patient registers or (2) self-reported depressive, burnout and schizotypal symptoms in 10,776 Swedish twins. Information was available on the years individuals played an instrument, including their start and stop date if applicable, and their level of achievement. Survival analyses were used to test the effect of musical engagement on the incidence of psychiatric disorders. Regression analyses were applied for self-reported psychiatric symptoms. Additionally, we conducted co-twin control analyses to further explore the association while controlling for genetic and shared environmental confounding. Results showed that overall individuals playing a musical instrument (independent of their musical achievement) may have a somewhat increased risk for mental health problems, though only significant for self-reported mental health measures. When controlling for familial liability associations diminished, suggesting that the association is likely not due to a causal negative effect of playing music, but rather to shared underlying environmental or genetic factors influencing both musicianship and mental health problems

Gene-environment interaction in expertise acquisition: Practice effects on musical expertise vary by polygenic scores for cognitive performance.

Expert performance is associated with practice, partly because of causal effects of practice on skill (i.e., learning). However, the practice-expertise association is also influenced by a complex interplay between genes and environment including partly overlapping genetic influences. The importance of cognitive ability in the practice-expertise association is less well understood. Therefore, we first examined whether genetic predisposition for cognitive performance, operationalized as a polygenic score, is associated with music practice and expertise. Next, we tested whether there is evidence for gene × environment interaction, i.e., whether effects of practice on expertise differ depending on an individual's genetic predisposition for cognitive performance. Polygenic scores for cognitive performance (PGScp) and multi-trait cognitive performances, including educational attainment and mathematical performances (PGScps) were calculated for approximately 3800 genotyped Swedish individuals with information available on their cumulative amount of music practice, musical achievement, and musical auditory discrimination. We found that higher PGScp and PGScps were associated with higher levels of achievement, musical auditory discrimination, and more practice, although the association with practice weakened when controlling for education. Music practice was linked to both expertise outcomes, and the effect sizes of these associations varied depending on an individual's PGScp and PGScps (with the exception of PGScp for musical auditory discrimination). These results suggest genetic pleiotropy between cognitive performance and musical expertise. Additionally, they reveal the presence of G × E interaction in skill acquisition, as effects of practice on musical expertise are stronger for individuals with a higher genetic predisposition for cognitive performance