We have "Open House" for the parents several times a year. You'd be surprised how many don't come. You probably wouldn't be surprised to know that very few of the students whose parents do come fail.
Blaming parents is a big excuse teachers started using in the 70's. However the great success of public schools was based on the ability to teach poor immigrant children in NYC. Their parents didn't even speak English. Schools became the great enculturating force, and they taught the children everything about how to be Americans. School was seen as the way up and out. Those children who have weak homes are the ones who need good schools the most. However, they need strong academics, not just free lunches.