My grandmother, who was born about 1900 and died in the late 70s, had an unusual cookie recipe called Chocolate Bran. After she died, my sister found her hand-written recipe and over the years she has tried to make the cookies, but they never taste right. There is the possibility that, since the ingredients have been changed over time (such as the way Crisco was made in the first half of the 20th century compared to the second half), that may have been a factor in the different taste. But my sister is convinced that there is an ingredient missing from the hand-written recipe, and she thinks my grandmother omitted mentioning it deliberately.
Do you have any family recipes that "don't taste right" when you try to make them? Do you think there were secret ingredients that died with the person who created the recipes?