Sharing personal info is a good thing because it help people to understand more about us. But it's also a bad thing when you share too much personal information.
If you share too much personal information, a lot of people will know, and the people that don't like you will know it too. Maybe they use those information to create a facebook, twitter,...account, and say some nasty things about people and maybe they add your friends and say some nasty about them. Maybe your friends will or won't know that's it isn't you. If they don't know, they will think that you really hate them so they won't play with you anymore.
In those information, maybe there are a lot of information that people don't need to know, for example you are in trouble with your friend, you shouldn't share too much on those social network because some people will identify with you, but some will be like: that's rubbish, we don't need to know it; solve it by yourself;... Some will tell you to do something bad with your friend,...
