Recently The Agency Gatekeeper made an observation that she's getting a large number of stories with similar themes.
I know why. Ideas are real objects. That's why, if you forget something, but go back to where you were last thinking of it, you will remember it again. It's nothing magical about the spot. The idea was just there, waiting for you, and you ran into it again. If you don't move fast enough, the idea moves on, and then someone else will stumble over it.
Sometimes, ideas do the multiple submission thing. Several people will get the same idea, at about the same time. (Look at the history of the light bulb.) The moral of that story is, when you get an idea, start writing. Because that idea may be sent out to several people at once, and then you'll all be submitting at once, and the gatekeepers everywhere will think "What's up with all the balloon stories this week?"
In a not entirely unrelated story, I gave one of my story ideas away last week. I've been thinking of the selkie story for years (literally). But I didn't want to write it. However, the idea wouldn't go away. I mentioned to one of my writing crit/partners in crime Building a Life, and she loved it. I knew that my idea had found its forever home and gave it to her right away. She wrote 10,000 words and checked in to make sure I really wanted to give it away. I did :)
I'm so happy that I found the right home for that idea. But now I wonder how many other people are foster parents for ideas, rather than the designated writer? Is there an idea that you don't want to write? If you could pick an ideal author for that idea, who would it be? Should there be a shelter for ideas that need a forever home?