Ghosts, skeletons, and vampires may give us the creeps this Halloween, but a fear of spiders is something we are all born with, according to a new study.

This fear, technically called arachnophobia (as the 1990 movie by the same name made famous), can cause crippling anxiety for some people and impact their daily life. For years, scientists have been trying to figure out why so many people are afraid of spiders, even in places where they hardly ever come in contact with them. While some experts assumed that we learn this fear from our surroundings as children, others believed it was innate.

Now scientists at the Max Planck Institute for Human Cognitive and Brain Sciences discovered that the fear is quite real and, in fact, hereditary. During their research, the scientists showed pictures of spiders along with more typically pleasing images, like flowers and fish, to a group of six-month-old infants. The scientists noticed that the children’s pupils dilated significantly when they looked at the spiders. Dilated pupils are a typical measure of the fight-or-flight stress response. The average pupil dilations were 0.14 mm when viewing the spiders, but only 0.03 mm for the flowers – a considerable reaction.

Remarkably, past studies found that babies did not have this same reaction when shown pictures of rhinos, bears, or other typically dangerous animals. This latest research, therefore, proves that babies as young as six months felt stressed out from looking at spiders long before they could have been taught to have this reaction from their parents or through experience.

The research team went on to conclude that arachnophobia has evolutionary origins. There is a part of our brain that causes us to identify certain objects as dangerous so we can react quickly in order to survive. This inherited stress reaction ultimately led to humans associate spiders with fear and unpleasantness, and that we must avoid them at all costs.

According to evolutionary biologist Gordon H. Orians in his book “Snakes, Sunrises, and Shakespeare”, many responses to our environment throughout history have been rooted in our survival mode. These experiences led to some of the ingrained, instinctual fears that are genetically programmed in us today.

Other common fears include snakes, microbes, pointed objects, leopard spots, rugged terrain, and eyes. Maybe it’s time to stop singing the “itsy bitsy spider” song to your littles, and definitely don’t dress up like a tarantula for Halloween.

In all seriousness, though, it’s crucial to understand where certain fears stem from so that we can address them properly with our children. Talk to your kids about their worries; if they bottle them up, it will only get worse. Let them know their concerns are common and that others experience them, too. Show that you understand what they’re going through by sharing your own personal anxiety stories, and reassure them that you’re there to support them whenever they become frightened.

It may take some simple distraction techniques to help kids overcome their fear instincts. If it becomes so bad that their fears interfere with their daily life, you may want to talk to your pediatrician.