How a person behaves is strongly affected by the environment and perception of the situation. Same person may have very different character traits depending on where geographically he or her are located, and in who's presence they are. It is sometimes referred as wearing different masks, different hats, or having multiple faces. It is easy to see this change of behavior in children. They behave very differently in presence of each of the parents, grandparents, peers, strangers, teachers and so on. Different combinations of people bring up different facets of personality in the individual. Some people have (as we say) no inner core (personality wise), meaning their conscience is undeveloped, their principles are weak, they change their mind and attitude depending on circumstances and don't stick to old loyalties and beliefs. If such people are egotistic and take advantage of others, their acts is usually bad of team morale and health of affairs. Yet, such people can regain good qualities in presence of good people with developed altruism and conscience. Many people don't have their own principles, but rely on peers and public opinion. These people are also affected by presence of good people with strong principles and conscience.
Hunger, tiredness and sleep deprivation affect much human's character. Some people become mentally stronger in crisis situations, others think less efficiently and lose the old principles and beliefs. It is easy to be altruistic when having a healthy life, but under physical and psychological pressure, people often lose their altruism.
Strong physical and emotional stresses sometimes wake up spirituality in people. Individuals who survived clinical death, had out of body experiences, are known to become more spiritual. More spiritual means their beliefs change to more of new age and lightworkers beliefs. They understand that there is life after death of the physical body, we are souls having physical experience. They become less dependent on propaganda and become wiser.