Jealousy is a human emotion that occurs from a dislike of a certain situation (such as someone cheating with your girlfriend) or selfishness. It's an inbred factor of human beings, as with all other emotions. Jealousy can be influenced by psychological, cultural and societal factors. A societal situation could be one in which a female gets jealous of another due to high fashion. Or a man being envious of a competitor who got a job that was open. It's all based on environmental, and at times, biological factors.