I will always share a recipe but one time my ex came over and asked for some of my recipes. I let her copy anything she wanted out of my hand written recipe book. This was before computers and the internet. Some time after she left, I discovered one of our favorites missing. I presume she stole it. When the internet came about, i found several recipes by the same name but they were different. Either someone had simplified the original or I had improvised some additions to the original which came from a magazine that said it was from a restaurant in California. I was able to recreate it to our satisfaction over time but I'd still like to see the one that was in my cookbook again.
I expect any recipe I give out to lose my name sooner or later. I got a recipe from a friend and always refer to it as her recipe even though she told me she got it from somewhere else.
Once there was a recipe that I gave out and the person asking was famous and my recipe is on her web site and attributed to me but she changed the recipe in a way that makes it not as good -in my opinion- even though people have told me about how much they enjoy it.
ps the above recipe was printed in a California news paper and they said it was from the famous lady.
I wish I could remember all the details of this one story I heard but it was about an aunt's fab. recipe for choc. chip cookies. She claimed it was an exotic recipe and gave it an fancy name. After years, the story teller discovered the recipe was the Toll House Cookie recipe.