We cry depending on the situations but is it voluntary (means it can be stopped, if we try) or its impulsive (We completely surrender to the sudden gush of emotion).

Really a thought provoking question! If it's impulsive, how men able to control it all the time??? If it's voluntary, how women find it hard to control it?..Maybe tears also have gender difference like some dif genetic make up!

Definitely, there is a genetic difference! Women need not hesitate to open the flood gates which produce spontaneous and slow results!!!! Men, seem to feel it unmanly to cry in public!Another important mark of Mars- Venus factor of genes.
voluntary or impulsive depends mostly on the situation but also on the person's temperament, a sort of 'proneness' like a dust allergy or nausea on uphill journey. Some people cry at the drop of the hat!!! Hypersensitive vareity! Some stand unmoved in the face of most cruel, passionate experience.