 10. Molecular Genetics of Personality  253
ants associated with personality have only 
just begun to bear fruits.
New technical and analytical develop -
ments already taking place in the field of 
public health and personalized medicine are 
expected to be applied soon to the genetic 
and neurobiological study of personality. 
These developments include next-  generation 
sequencing, genomewide gene expression 
and epigenetic studies, omics studies, im -
aging studies, and big data approaches that 
combine data at these different levels (Auf -
fray et al., 2016; Eisenstein, 2015; Thomp -
son, 2019). Such developments will likely 
lead to novel insights into the molecular 
genetics of personality but should not pre -
clude more traditional research directions 
that continue to be important: carefully 
designed longitudinal studies with lifespan 
approaches to personality development, as 
well as fine-  grained studies that incorporate 
detailed assessments of environmental fac -
tors that could explain the remaining part 
of the variance in personality that is not 
attributable to genes. Ultimately, and sup -
ported by twin-  family studies on personal -
ity that highlight the importance of gene– 
environment interaction and correlational 
processes (Krueger & Johnson, Chapter 9, 
this volume), these lines of research (molec -
ular genetics/omics approaches vs. environ -
mental/longitudinal approaches) should not 
just be further developed independently but 
should brought together in multidisciplinary 
collaborations. A challenging task will be to 
interpret the findings such multidisciplinary 
big data analyses will yield in the context 
of existing theoretical frameworks on per -
sonality. Hopefully, these proposed future 
directions for the (molecular genetics) study 
of personality will further contribute to our 
knowledge on the development of and indi -
vidual differences in personality, and how 
personality is related to important life out -
comes such as mental and physical health, 
and human well-being in general.
NOTES
1. Mitochondrial DNA is found in the cyto -
plasm of the cell, and is not discussed further in this 
chapter.
2. Other types of genetic variants exist, such as 
copy number variants or rare mutations, but since they have not been studied (yet) in the context of 
personality, they are not discussed in this chapter.
3. But family-  based association methods are also 
available.
4. More recent candidate gene studies also have 
examined the additive effects of multiple genetic 
variants within the same gene or a cluster of related 
genes in a so-  called “polygenic” risk analysis.
5. Along with results for genetically correlated 
phenotypes for well-being and depressive symp -
toms.
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