Teenage is an age where the children will think that they know everything and what they know is only correct. In addition to that the family background and the way in which these children were brought up also will have a big say on their behaviour. Parents are the best judges of their children. So parents should encourage their children to do well in their education at the same time they should be taught the importance of ethics and values in life. Once they understand these issued the children will always be in their limits only.
Now everyone has become responsible and I don't think we should prevent them to have a get together as we can assess the people with whom our children are making friendship. The nuclear family structure too has prompted to such type of gatherings as we are all running out of time to spend with our children and our relatives too.
Knowledge is power.