This was something that never rang true with me either. The explanations that were given were at best wishy washy and at worst just plain weird.
I did some research myself on Birthdays, (especially in line with the "Pinata" case recently!) and I have to admit I was quite surprised with what I found.
I have pasted the article here (well I'm going to try and paste it here!):
The German periodical "Schwäbische Zeitung" (magazine supplement Zeit und Welt) of April 3/4, 1981 on page 4 stated: "The various customs with which people today celebrate their birthdays have a long history. Their origins lie in the realm of magic and religion. The customs of offering congratulations, presenting gifts and celebrating - complete with lighted candles - in ancient times were meant to protect the birthday celebrant from the demons and to ensure his security for the coming year. . . . Down to the fourth century Christianity rejected the birthday celebration as a pagan custom."
The book The Lore of Birthdays (New York, 1952) by Ralph and Adelin Linton, on pages 8, 18-20 had this to say: "The Greeks believed that everyone had a protective spirit or daemon who attended his birth and watched over him in life. This spirit had a mystic relation with the god on whose birthday the individual was born.
The Romans also subscribed to this idea. . . . This notion was carried down in human belief and is reflected in the guardian angel, the fairy godmother and the patron saint. . . . The custom of lighted candles on the cakes started with the Greeks. . . . Honey cakes round as the moon and lit with tapers were placed on the temple altars of [Artemis]. . . . Birthday candles, in folk belief, are endowed with special magic for granting wishes. . . . Lighted tapers and sacrificial fires have had a special mystic significance ever since man first set up altars to his gods. The birthday candles are thus an honor and tribute to the birthday child and bring good fortune"
This same book, on page 20, also had this to say about the traditional greeting of 'Happy Birthday': "Birthday greetings and wishes for happiness are an intrinsic part of this holiday. . . . originally the idea was rooted in magic. The working of spells for good and evil is the chief usage of witchcraft. One is especially susceptible to such spells on his birthday, as one's personal spirits are about at the time. . . . Birthday greetings have power for good or ill because one is closer to the spirit world on this day."
And Horst Fuhrmann, professor of medieval history at the University of Regensburg, made this comment about birthdays: "The birthday celebration was in honor of one's guardian angel or god, whose altar was decorated with flowers and wreaths; sacrifices were offered to the god of festival, friends offered congratulations and brought gifts." Furthermore, he stated in the German newspaper "Süddeutschen Zeitung": "Great prominence was given the birthday parties held for the emperor, replete with parades, public banquets, circus plays, and the hunting of animals: spectacles disgusting to the [early] Christians."
Wow" It worked!
Anyway, why don't they use this kind of information instead of the usual "Bad light" theory. I'm inclined to agree with them (heaven help me!) on this principle merely because it's quite plainly steeped in paganism and being a Christian the two don't marry together for me.
But surely if they were to use this line of reasoning then it would stand up a bit more under scrutiny (not to mention, the no doubt, hundreds of JW's who can't quite understand why birthdays are wrong but follow the rule anyway whilst secretly doubting!)
Anyway, that's my two penny worth.
All the best
Laurelin