Yep that was because I had the same thing my friend had, so I thought to recommend what I was already taking but they refused and saw the dr. Dr told them to take literally exactly the same thing I was already taking.

They didn't say, "Sorry I didn't listen to you" or the like. I was saying "I told you so!" deep inside but I just smiled at them when they told me what the Dr said.

As for your MIL, yeah, people can be that feeble enough to trust anyone who have a degree/diploma and is an "expert" at what they do, without even trying to do the research on their own. Little does they know that people can be an "expert" just because they memorized everything in the book but they may not understand 1/2 of it!

But to each their own!