I know SE'rs love mixing food-related in-law stories. Here's something that's going viral.
You can read the email from a future MIL to a bride-to-be here.
I paste the food-related part:
When you are a guest in another's house, you do not declare what you will and will not eat - unless you are positively allergic to something. You do not remark that you do not have enough food. You do not start before everyone else.
You do not take additional helpings without being invited to by your host.
While this mom-zilla is super scary, I'm kinda with her on picky eaters (I will not tell or email my comment to a person, however).