I enjoyed this story, from the introduction to I Didn't Know That: From "Ants in the Pants" to "Wet Behind the Ears"--the Unusual Origins of the Things We Say by Karlen Evins. It's

… about a young bride preparing her first Thanksgiving meal under the watchful eye of her new husband. When she got to the holiday ham, she systematically cut off the ends and placed them in a pan. Her new husband, not certain of the proper cooking procedure for hams, asked his bride, "Why did you cut off the ends?" Her reply: "Because my mother always did."

Later that day, the mother of the bride showed up early to help, and the newlywed husband … pulled his new mother-in-law aside and asked, "It all makes sense; but why did she cut off the ends of the ham before cooking?" With as much consideration as the daughter had given the question earlier, the mother-in-law answered, "Because my mother always did."

Finally the meal was prepared, the guests were seated, and in the mix of the conversation, the grandmother of the bride was posed the same question by a now most curious grandson-in-law. "Grandma, just one thing . . . why the endtrimming before you cook a ham?"

With aging hands, the grandmother held hers up, gesturing before him, and replied, "Well, in my day, the pans were only this big!"

… our reasons for many of the things we do today make little sense logically, though at one time, perhaps they did.

ory. Each

Thanksgiving HAM? That's the first thing that doesn't make sense.

I've heard several versions of this parable, variously involving gorillas, Space Shuttle boosters, or biplane cockpits that smell like horse droppings.