My dad and my father in law were both bad about doing this. They would even ask a question, and interrupt before you were able to answer it.

I realize that for some people it isn't a big deal. My wife is one of them. Her family is what my daughter calls 'competitive talkers'. Who ever talks the loudest, interrupts the most, or completes the other person's sentence wins. Myself, I find it rude. And I Just won't put up with it.

I adopted the practice many years ago of withdrawing myself from the conversation if the other person interrupts or talks over me twice. You've just shown you have no respect for my opinion, or you're simply not interested in what I have to say.

It drives my wife nuts. Sometimes she can't help herself. After 32 years, she'll still interrupt, or try to finish my sentence.

I'm kind of quiet anyway. Silence doesn't bother me.

Now if they interrupted with something like, "My god! It's going to kill us!" That would be a different story.