sooner or later
This expression is used to state that something is inevitable and it will happen eventually. There is a Turkish equivalent for this expression.
Teenagers and young adults have the tendency to blame everyone and everything for the bad things happening in their lives except for themselves. Sometimes they blame their parents, school or friends when things are not going well. However, sooner or later they grow up and learn to take responsibility for their own mistakes. I guess this is when the parents become the happiest.