Youth Wants to Know...

... Is a pair of twins two or four persons????

That question has been needling this youth and a few of her youthful companions ever since a fateful visit to the old facts section of the reference department. Here I encountered George W. Stimpson's fantastic and fantastically random 1928 book Nuggets of Knowledge. The entry on the aforementioned question caught my eye, but I was so dazzled by all the other nifty nuggets (such as "If a tree should fall in a forest thousands of miles from any living creature, would any sound be produced?" and "Why does a salute consist of twenty-one guns" which, oddly, are the nuggets that precede and follow the twins question), that I didn't bother to actually read the entry. So, for those of you who have been losing sleep over this burning question, here is his answer:

Is a pair of twins two or four persons?

The word twin as a singular noun is generally defined as "one of two children or young brought forth and birth." The plural form twins is defined as "two children or young brought forth at one birth." Logically speaking, then, a pair of twins ought to mean four children. But it does not and never did. Nobody uses the expression to mean more than two. When a speaker or writer employs the phrase pair of twins he invariably means exactly what he would mean if he said merely twins. "Mrs. Jones has a pair of twins" and "Mrs. Jones has twins" are identical in meaning. Since the word pair adds nothing to the sense, why not say simply twins? It cannot be questioned, however, that pair of twins for twins is widely used in popular speech and has some literary support.

So, basically, a pair of twins is like a pair of pants.