Smiling can be frowned upon in some countries

[elte]

http://www.businessinsider.com/why-some-...ile-2016-5  --  

 He found that in countries like Germany, Switzerland, China, and Malaysia, smiling faces were rated as significantly more intelligent than non-smiling people. But in Japan, India, Iran, South Korea, and—you guessed it—Russia, the smiling faces were considered significantly less intelligent. Even after controlling for other factors, like the economy, there was a strong correlation between how unpredictable a society was and the likelihood they would consider smiling unintelligent.

[C C]

Easier to believe that culture / custom and unreliable social agencies would have more to do with it than that the bulk of their populations happen to have the long allele on the 5-HTTLPR gene.

Quick to laugh or smile? It may be in your genes
https://www.sciencedaily.com/releases/20...082543.htm