the idea of being afraid or wary of the number thirteen (Triskaidekaphobia, for those who like fun words), is a left-over from pagan culture. Thirteen is a very luck number for Christians and Jews (the Thirteen Attributes of God's mercy from Exodus 34 and Psalm 80), and is lucky to Muslims for the same reason. Further, the thirteenth day after death, Hindus organise a feast for the departed - a good thing. Additionally, for Sikhs, thirteen reminds them of Guru Nanak Dev Ji and his generosity.
If you go through religious behaviour, thirteen is a very lucky number. It is very strange that it is from native North-American culture that the negative concept of thirteen grows - they have a belief that there are thirteen cycles of misfortune.
This fear of thirteen has spread through North America and Europe thoroughly, also touching other continents. But it came from a small Native band in Arizona.
There is way more information than anyone wanted.
Anyone know how Schoenberg is relevant to this conversation?
(and now my geekiness is fully revealed)