Actually, I've no quarrel at all with the bodhran story, though they seem also (perhaps more often?) to have been made pro tem by simply tacking a skin to a farmyard riddle. As for that Pagan Rite business; well, it could be true. There's no evidence that holds water, though, so we really shouldn't state it as some sort of fact, as it's nothing of the kind; just a theory, though an often-repeated one.

The thread DTStudy: Cutty Wren probably contains the best information available here (and some of it more reliable than you'll find almost anywhere on the web, though it does have its fair share of silliness as well); together with links to some other discussions here and elsewhere.