Why is 13 considered unlucky?

Answer 1

13 is really only considered unlucky because a mass group of people deemed it as such several thousand years ago during the height of the Greek empire. Most of our current society is based on Greek culture and the Greeks had 12 as their lucky number. So many people had 12 as their lucky number, hence anything over 12 was considered bad luck. Indeed, many cultures identified 12 as lucky, the same way we deem 7 as lucky. Why would you want 13 of anything when 12 is such a perfect number?

This is shown in many mythologies, such as that Hercules completed 12 labors. The first clocks were based on the idea that there was 12 hours of day and 12 hours of night. And in Norse mythology, 12 Gods were invited into Valhalla, the Hall of the Gods, but Loki snuck in and killed Baldur using Mistletoe, Loki being the uninvited 13th Guest.

There have historically been some instances of bad luck associated with the number 13, such as Apollo 13 or the Last Supper having 13 guests and indeed some people do believe as such that 13 is unlucky. But often, I seriously think that 13 gets a bad rap. People are more prone to blame something if the number 13 was somehow involved. Like if someone breaks their leg on the 13th floor of a building, they'll say "This is proof that 13 is bad luck" but if they break their leg on the 21st floor, they'll say "OWW! This was my terrible luck".

Answer 2

I'm born on August 13th...