Note sure if I understand what you mean?

You mean that we showed them already by that age to not mix fries & ketchup? :-D If children are that small and you are sitting with two of them at the table, handing over those ideas to them in a "nurturing way" is the last thing on what you can focus on with two small kids at the table :-))

And its always great if someone gives a downvote here if you share some personal life stories :-D

I believe that GP is trying to say that your child picked up that behaviour by watching you.

Monkey see, monkey do. (No offence intended towards your child.)