Years ago, i read a paper that looked at a database of all known organic molecules, and found that a disproportionate number of them had an even number of carbon atoms. I can't find it now, of course.

The paper was a similar "that's funny, i wonder why" sort of piece. The tentative explanation i remember is that a lot of those organic molecules are natural products, and the nature of biosynthetic pathways is that they tend to add carbons two by two. Which i don't think is even true - terpenoids are built five carbons at a time.