The royal family, like any other, has its own superstitions and beliefs. Here are some of the more unusual among them.

Step on a crack, break your mother's back. Don't walk under a ladder. Terrible things happen on Friday the 13th (besides low-budget slasher films).

Where do superstitions come from and why do people still hang onto them?

After much research and falling down Google rabbit holes, it has been determined that many scientific types believe superstitions grew out of humans' need to understand the world around them.

An article in the 2018 International Journal of Psychology and Behavioral Sciences states, "Superstition has its roots in our species' youth when our ancestors could not understand the forces and whims of (the) natural world. Survival of our ancestors was threatened by predation or other natural forces."

In other words, they made up explanations -- whether rational or not -- to explain the inexplicable.

As a result, superstitions have "evolved" to produce "a false sense of having control over outer conditions," and reduce anxiety. This is also why superstitions are "prevalent in conditions of absence of confidence, insecurity, fear, and threat."

But superstitions aren't necessarily a bad thing. In fact, some experts say luck-boosting rituals like knocking on wood or carrying a rabbit's foot can be beneficial. Stuart Vyse, a former psychology professor and author of "Believing in Magic: The Psychology of Superstition," said during an interview for the British Psychological Society:

"There is evidence that positive, luck-enhancing superstitions provide a psychological benefit that can improve skilled performance ... (t)he absence of control over an important outcome creates anxiety. So, even when we know on a rational level that there is no magic, superstitions can be maintained by their emotional benefit."

Let's explore eight superstitions, some of them garden-variety, others a bit more esoteric.

According to various sources, the belief that breaking a mirror brings seven years of bad luck dates back to ancient Greece, where it was common for people to consult "mirror seers." These seers told people's fortunes by analyzing their reflections, a practice called catoptromancy.

A sick person was asked to look into the mirror. If their image was distorted, they likely would die; if it was clear, they would survive.

Where's the 13th floor?

Several theories surround the origins of this well-known superstition. Moira Marsh, a folklore librarian at Indiana University Bloomington, said on NPR's "Morning Edition" that the concept of 13 as unlucky didn't show up until around the 17th century.

Before then, it might have been seen as good because it reportedly goes back to the 13 people at the Last Supper. However, after the Reformation, such beliefs were forbidden as superstitious, Marsh said.

But forbidden doesn't mean forgotten since lots of people still consider the number unlucky. For example, many (if not most) buildings exclude the 13th floor from their elevator panels. There's even a name for the fear or avoidance of the number 13: triskaidekaphobia. (Say that 13 times fast!) Fear of Friday the 13th specifically is paraskevidekatriaphobia or friggatriskaidekaphobia.

Don't be a scaredy cat

Historically speaking, black cats just can't catch a break. What's now known as "black cat bias" took root centuries ago.

In Greek mythology, Hera (Zeus' wife) transformed her servant into a black cat out of anger. The servant, Galinthias, went on to serve Hecate, who presided over magic and spells. Translation: Hecate was a witch. And speaking of ...

Witches were often accompanied by feline sidekicks to assist their evildoings in some European folklore. It was also believed that witches could transform into black cats to cast spells on people. During the Middle Ages in Europe and the Salem witch trials, both witches and black cats were persecuted and killed together.

Superstitions still persist (purr-sist?) about black cats, but there are countries in which the ebony felines are seen as symbols of good luck -- Ireland, Wales and Japan among them.

In the U.S., the tide against black cats also is turning, with shelters and rescues leading the battle against the bad rap they've gotten. Adoption rates have increased over the years, though still lower than cats of other colors. But those other cats can't boast their own day; National Black Cat Day is Oct. 27.

A bone to pick

We've all gotten the wishbone at some point and as if by instinct, we knew it was meant for a two-person tug-of-war. How did we arrive at this method of getting our wishes granted?

Superstition expert Benjamin Radford told Yahoo! Health that fowl once were used as tools of divination. Soothsayers would examine the entrails of a recently killed bird, a practice called haruspication, then save the collarbone. One person would wish upon the bone and snap it with another person. Whoever got the larger piece was believed to have received a sign that the gods heard them.

Not-your-everyday superstitions

Some superstitions are more specific than universal, generated within a particular culture or region of the country and sometimes, even within our own families. Here are a few less common (but no less outlandish) beliefs and sayings:

If a bird steals a strand of your hair to make its nest, you will have headaches. The origins of this superstition are unknown, but this writer heard it often as a child during hair-braiding sessions on the back porch. According to legend, you're supposed to burn any loose hair left in the comb or brush and scatter the ashes, which was thought to be reserved for killing a vampire.

An owl flying over the house is an omen of a death to come. This belief was handed down through the oral tradition of Paschal indigenous relatives. For some Native American tribes, the great horned owl was the most feared of the species. In fact, the Cherokee word for witch (tskilu') is the same as the word for great horned owl.

If it rains while the sun is shining, the devil is beating his wife. According to most sources, this belief has its roots in the southern U.S., which tracks since it was perpetuated in the Paschal household by two Southern parents. However, The Idioms reports it was first used in a French stage play in 1703, then by writer Jonathan Swift in 1738 and again in Richard Inwards' book, "Weather Lore."

A man must walk into the house first on New Year's Day. In several cultures, who walks through your door first on New Year's Day is the key to prosperity and good fortune. Known as the first-foot or first-footer, this person is usually male, though details vary from place to place. In most places, the first-footer must be dark-haired, whereas some stipulate fair hair. Also, some cultures specify a married man, while others insist on a bachelor.

First-footing is prevalent in Scotland, where it often comes with gifts and entertainment. Similar practices are found in countries including northern England, Isle of Man, Greece, Vietnam and in some parts of the United States.

For most of us, superstitions are little more than harmless hokum. Or are they? Despite what our rational minds tell us, it's still difficult to shake some superstitions. We know they're silly, but why tempt fate? Not that I'm worried, mind you. I have my lucky rabbit's foot -- just in case.