You might have heard about the interesting fact that the decline in the number of births looks similar like the decline in the number of storks... and as every legend-savvy German knows, it's the stork that brings the babies. So. No more storks, no more babies, right?
Just that correlation is not causation. Nicest and funniest bit about that that I know is this XKCD:
And if you're amused by spurious correlations, there's a whole website about this that you might enjoy!