From avoiding walking under ladders to never letting a black cat cross your path, superstitions are often dismissed as a fool's game.
But one common 'irrational belief' could be proving very costly - and it's bad news for some homeowners.
The number 13 is considered unlucky in many cultures around the world and even has its own word; triskaidekaphobia.
Now a study by new homes specialists, Stone Real Estate, has found that properties with number 13 sell for significantly less than other homes and some housebuilders have now chosen to remove it completely from new developments.
It found existing number 13 properties have sold for an average of £22,006 less than others since 2016 - a huge reduction of 8 per cent.
New build homes have done better to shake the stigma but still sell for 2 per cent less than its luckier neighbours.
House-hunters may be avoiding homes with 13 on the door, with the number accounting just 0.8 per cent of new build sales and 1.1 per cent of existing property sales in the same time period.
Although number 13 new build homes have actually sold for 0.2 per cent more than average in 2019, existing homes bearing the number again sold for 8 per cent less than average - wiping a whopping £21,908 off its value.
Founder and CEO of Stone Real Estate, Michael Stone, said: "In this day and age, it’s quite remarkable how ancient superstitions can still have such a detrimental impact on the price a property will sell for.
"For many, the aspiration to own their home will no doubt rise above any such feelings around the number 13 and the figures show that as a first-time buyer, it’s probably the ideal number due to the lower cost of getting on the ladder.
"However, there are signs that this tide is starting to turn within the new build sector at least, and so far this year, the number 13 seems to be in vogue with slightly higher sold prices."
