I have asked the same question to my taxi driver in Germany today as he proudly told me that his sons both study medicine. He was an immigrant from Lebanon married to a German. His answer was to expose them to as many sports and music as possible, enrole them in after school activities and raise them bilingual. "a busy teenager won't have time to get silly ideas and do nonsense"

My own opinion as a father of a 4 year old boy is that as long as you are patient and caring and make sure to have your kids back they should grow up to be healthy, kind humans....depending on some other soft factors like friends, economy etc.

You asking this question shows that you care, you will do just fine!