I heard a similar one, about a woman who had learned from her mother always to cut the ends off the roast before putting it in the oven. One day, teaching her daughter about how to cook a roast, her daughter asked why, and she realized she didn't know - so she went to her mother.
Her mother said, "I always thought it was for the taste, but I learned it from your grandmother; we should ask."
So they asked the grandmother, who said, "Oh, when your father and I got married, all we had was a very small roasting pan, so I cut off the ends of the roast so it would fit."
This is basically the origin of all religions, especially 'modern' monotheistic ones.
Good, sensible ideas (at the time!) get codified. Throw in a charismatic leader of some kind who (apparently) goes around trumpeting these smart ideas. Voila, religion.
Any dead religion is by definition not a modern religion. If you look at religious movements started within the last 50 years in the U.S., there are few if any that fit that pattern.
A religious scholar was telling his wife about the interesting discussion in class one day.
"We were attributing the reason for removing the chicken's legs before cooking it for soup."
"Reb Schalcter said it was to follow the dietary laws laid out in Leviticus."
"Reb Abraham said it was to help us retain our compassion because an innocent animal had to suffer for our benefit."
"Reb Zalman said it was because the legs were most likely to be diseased."
"I said that it was to remind us that the world, like the chicken, is broken."
"What do you think?"
His wife responded, "So that it fits in the pot."