Is There Anything a Wish Can't Do?
"Only as I tried and failed and failed again did I realize what you're suggesting: some things can't be gotten by wishing."

Our resident genie returns for his regular advice column.
Dear Genie,
Can I wish for anything I want, or are there things you can't get from wishing?
Sincerely, Porsche, age 8
Dear Porsche,
Way to get right to my insecurities. You know how to pick at a scab, don't you.
Alas, I admit the wisdom in this question, and I congratulate you, Porsche, on being much quicker to ask it than I was. When I was younger (mere hundreds of years old) I thought I could give anything to anyone. If I failed to "stick" a wish, I blamed myself. If I were cleverer, I thought, the wish would have gone to plan. Only as I tried and failed and failed again did I realize what you're suggesting: some things can't be gotten by wishing. Or if they can, they won't stay, or they lack the sweetness they might have had.
The biggest example comes first to mind: You can't get love or friendship by wishing. (Technically.) That might be surprising, but it's true. Love and friendship must be given, and a granted wish is always a kind of taking. Genies don't see this as a problem, though. You can still grant the wish. You study the love-interest's needs, tastes, fears, et cetera, and you change the wisher in appearance or circumstance so they fit the object's image of the perfect friend or lover. Easy. Except for the wisher, who's on his own to stoke those embers of affection. There are ten thousand movies on the topic, including my least favorite movie of all time. (It's an animated musical. You can guess.)
There's another category of wishes I call "wishing for a soapbox car." (I used to call it "wishing for an Oslo sled," but nobody gets that reference anymore.) If you want to join a soapbox derby, I can give you a car, no problem. I can even make sure you win. But that's not the point of a soapbox derby. The point is to go careening down a hill in a car you designed in your own little head and built in your garage on a shoestring. Now, surely, it's better to wish for help with your car, than to wish for the car itself, but wishing for an automotive engineer is still "wishing for a soapbox car," in my opinion. On the other hand, wishing for a garage is not "wishing for a soapbox car." Nor is wishing for a shoestring, if you don't have one. Those are fair game. And this is a metaphor, if that's not clear.
Now let's come to a hypothesis I'd love to disprove: Some things can't be wished away forever. (Including polio, apparently, though I really, truly tried.) I vividly remember the young French girl—close to your age, Porsche—who asked me to drive the Nazis from her village. Her wish came true, and I think she'd tell you it was well spent. I thought it was well spent, even though, as I arranged things, I knew it couldn't last. I've chased away too many kinds of Nazis from too many villages to believe they'll be gone for good. That little girl is still alive, and the Nazis are back in her village, though they didn't come as invaders. It's a cosmic mystery, how often a wisher's grandchildren put on the very uniforms their grandmother wished away.
What else? Let's see. Oh, gardening—that's an interesting one. I can make someone a hotshot pilot, a graceful dancer, almost anything else, but I can't make you a great gardener. It's an old magical injunction. When you see a marvelous garden, you can be 100% sure the gardener got there the hard way. The same is true of Sicilian cooking, though that's a special case. Most of the great French chefs have been acquaintances of mine.
And that's about all I can think of. You can get most anything else by wishing, if you get the chance. And best of luck with that.