leilakalomi

I have been thinking about the people around me a lot lately and I am wondering is emotional instability something that is built into each person that exhibits it, or is it possible that emotional instability is something that can be transmuted from one person to another?
I walked into a room today and when I went in myself and all those who were already there were happy and having a good time. Then another friend joined us. In less then 10 minutes the mood of everyone had deteriorated greatly. The last person to join the group threw a hissy fit and left the room, but only after upsetting myself. My mood change then upset another friend and he and I had an argument, which in turn upset another friend who does not like it when her friends fight. It was not long until we had all separated into different directions.
Having removing myself from the area I am now calming down. I just wonder if being near someone in a bad mood will cause their emotions to effect the emotions or those around them and cause a room full of instability.
Any thoughts I on this idea? I would be interested in hearing them.