Short alleles, bigger smiles? The effect of 5-HTTLPR on positive emotional expressions
Emotion (2015) - Comment
pubmed: 26029940  doi: 10.1037/emo0000074  issn: 1931-1516  issn: 1528-3542 

Claudia M. Haase, Ursula Beermann, Laura R. Saslow, Michelle N. Shiota, Sarina R. Saturn, Sandy J. Lwi, James J. Casey, Nguyen K. Nguyen, Patrick K. Whalen, Dacher Keltner, Robert W. Levenson