The similiarity of facial expressions in response to emotion-inducing films in reared-apart twins.
BACKGROUND
While the role of genetic factors in self-report measures of emotion has been frequently studied, we know little about the degree to which genetic factors influence emotional facial expressions.


METHODS
Twenty-eight pairs of monozygotic (MZ) and dizygotic (DZ) twins from the Minnesota Study of Twins Reared Apart were shown three emotion-inducing films and their facial responses recorded. These recordings were blindly scored by trained raters. Ranked correlations between twins were calculated controlling for age and sex.


RESULTS
Twin pairs were significantly correlated for facial expressions of general positive emotions, happiness, surprise and anger, but not for general negative emotions, sadness, or disgust or average emotional intensity. MZ pairs (n=18) were more correlated than DZ pairs (n=10) for most but not all emotional expressions.


CONCLUSIONS
Since these twin pairs had minimal contact with each other prior to testing, these results support significant genetic effects on the facial display of at least some human emotions in response to standardized stimuli. The small sample size resulted in estimated twin correlations with very wide confidence intervals.
Kendler
K S
KS
Department of Psychiatry, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA, USA. kendler@vcu.edu
Halberstadt
L J
LJ
Butera
F
F
Myers
J
J
Bouchard
T
T
Ekman
P
P
D000328:Adult; D000339:Affect; D002648:Child; D002668:Child Rearing; D005149:Facial Expression; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009040:Motion Pictures; D014427:Twins / Q000235:genetics* / Q000523:psychology*; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D014796:Visual Perception