Cheese grows on trees

Back at the Green County Fair, Firstborn actually asked me if I was planning on planting some cheese now that I had seen the garden entries. I don't know where he got this idea as there were no bricks of cheese among the cucumbers, beans, and corn on display. I stopped quickly and looked at him to see if he was joking. There was no sign of humor on his face.
I confess, my child thinks cheese grows on plants. I have failed miserably as a mother. At least the COSI show at school this year was on dairy farming. So Lastborn knew better. However, when the presenter included in his talk that Bessie (the life size, milkable model of a cow) and her brothers and sisters get milked twice a day, I vowed that my children would never be so ignorant of where their food comes from. I was under the impression that my sons had some idea of where their food comes from. They might not know that only the females give milk, but they should know that milk does not grow on plants!
Sigh.
A gaff like that can't be ignored; especially when it comes from a child who is so incredibly intelligent and intellectual. Certainly, the younger brother will not let this chance go by. He reminded Firstborn at dinner last night that Firstborn thought cheese grew on plants.
"No," firstborn replied, "it comes from trees."
He likes to cover up his embarrassment by making out that he is telling a great fantasy story. So making the gaff larger makes it harder to believe he seriously made such a mistake in the first place.
"Cheese doesn't grow on trees, it comes from cows," Lastborn replied.
"No, cheese doesn't grow on trees, cows do and cheese comes from cows," replied Firstborn. (Great, we finally got one right.)
At this point, I had pictures of cows floating on the ends of branches high up in the trees.
Being the insightful child that he is, he continued on. "And the buildings all have to be made of steel in case the cows fall out.
Now, I've got a visual of cows falling from trees. "That would make fall kind of dangerous don't you think? You couldn't walk outside while the cows were falling from the trees, and all you would hear all day and night would be splat, splat, splat, as they hit the ground."
At this point the boys are laughing. There's nothing funnier to a boy than cow carnage (except maybe toilet humor). So i continued. "Do you think the leaf blower would be useful? I mean it could only do so much in blowing the cow guts off your lawn.
Dinner was over at that point and now it is a given; cows grow on trees.