Los americanos no pueden sonreir en las fotografías de sus pasaportes. Ignoro si aquí se permite pero, aunque tenga su lógica, me ha hecho gracia.
Como suele pasar con estas cosas, ya lo han contado otros. Os copio fragmentos del artículo sobre el tema en el USA Today:
The new guidelines permit people to smile for passport and visa pictures but frown on toothy smiles, which apparently are classified as unusual or unnatural expressions.
"The subject's expression should be neutral (non-smiling) with both eyes open, and mouth closed. A smile with a closed jaw is allowed but is not preferred," according to the guidelines.
Smiling "distorts other facial features, for example your eyes, so you're supposed to have a neutral expression. ... The most neutral face is the most desirable standard for any type of identification," said Angela Aggeler, spokeswoman for the State Department's Bureau of Consular Affairs, which handles travel-document guidelines.