My in laws are very polite. They might give their opinion once on an issue, but they don't say anything negative once they know our position. For example, when I was pregnant for the second time and my husband mentioned to his mother that I wanted to have a homebirth, his mother said that she thought we should think it over and do it in a hospital as she thought that was safer. Interestingly enough, her father was a country doctor who delivered women at home. That was the only time she made a comment, and that was to my husband. When he told his parents we were having a homebirth, they were very polite about it. They seem to be normal people with a live and let live attitude. Some of the in laws I read about here seem psychotic. I used to think that was an aberration, but it seems to be more common than I would have thought.
My own mother is a little more in the other camp, but not too bad overall.