Some parents are lazy. To build up a good manner to kids, parents need to spend most of their time to handle that. It is very hard to pay attention on your kids all the time. Some parents don't really know how to communate with kids. That's another problem. Kids won't listen to you unless you can understant them.
seriously agree. I thought I could train my son well when I was single. Afterall, every single one of my family works in education but that proves to be an incredible tough job.