Actually some enthusiastic home cooks, and definitely professional chefs, are interested in recipe origins.

Whoever wrote in the cookbook must have also adapted from someone, somewhere. Cookies are in existence for years. Either the writer got it from her mom or grandmom or some other recipe or someone else! But he still calls it as his recipe! So, why can't you?? Cookies have standard ingredients - flour, butter, sugar and maybe baking soda. What's the big deal in calling or not calling it as yours?

I don't think your friends care where you got the recipe from, they just want delicious cookies, so no ned to put the adapted from… at the end.

^^Your friends

You're friends just want the recipe. They don't care where it comes from. No one cares if you credit the source when you give the recipe to a friend.

OP,

I think it's change 3 ingredients entirely, not change the proportions but I'm not sure, I heard this at a conference years ago. In my case, I make these cookies, I added two new ingredients, used nutmeg instead of cinnamon. That's new but I credit the original.

Just curious: Why are you asking?

I shared a recipe with a friend and she posted it on DCUM as "her" recipe. I know it's petty but I was peeved.

If you're just giving it to friends, who cares? Presumably, they like the recipe the way you make it, so they aren't going to care where the original recipe came from.