Manners and good behavior should come from the parents. Teachers are responsible for things like math, science, and reading. Teachers can help to guide the students along a path of better behavior and manners, but that foundation has to come from the parents. If it doesn't, there isn't much a teacher can do in the classroom other than manage the bad behavior.
Ive worked with students, teachers and parents on a variety of levels. I always find I can pick out the kids who have little guidance at home. While on a field trip they are unruly, loud, over dramatic. They push for my attention in any way possible, including negative attention. And when their parents are along for the field trip, It's easy to pair up who belongs with who. "Good behavior" is a fundamental lesson.. how to behave in society.. and is something that should be taken on by the person who spends the most one-on-one time with the child - his parents.