No. Not even remotely. Teachers do provide a good example for their students, but it's not their responsibility to watch children 24hrs a day to ensure good behavior, to inspect their home to make sure it's suitable, to watch their parents and ensure that they're not abusive or setting a bad example. If we give them a "fair share of the blame," then their share would be exactly 0%, because they are not responsible for the problems they and their students have to deal with.