Weird traits Geminis all share

If you're born between May 21 and June 21, and have a personality that friends and loved ones can only describe as unique, contradictory, and downright weird, you'd likely be considered a typical Gemini, whose house is ruled by the planet Mercury, and whose sign is a pair of twins (via Zodiac Thing).

Stars Like You says people under the Gemini sun signs are often driven by curiosity and a drive to express themselves. Because Geminis are versatile, they are adaptable, flexible, and enjoy constant change — from something as simple as an outfit to more complex matters including friendships, associates, and potentially important decisions.

One thing that sets a Gemini off is conflict. If their flightiness drives your crazy and you pick a fight because of that, you can expect a Gemini friend or loved one to turn and walk away before the fireworks really get started... leaving you wondering why they chose to abandon ship the way they did (via Zodiac Fire).

Geminis are often impulsive and cannot commit

If you have a friend that loves changing his or her mind at the last minute (and your plans as a result), you're probably looking at a Gemini. People born under this sun sign are naturally impulsive, which will explain why no destination is ever final with a Gemini, and how they are able to hone in on (and pick up) something they may not be able to afford. 

Geminis are known for their ability to make multiple suggestions involving a dinner arrangement — only to settle on something different entirely. This impulsiveness makes it difficult to date a Gemini because if he or she can't settle on a restaurant, you aren't likely to get a Gemini to commit to a future together (via PrepScholar)

Geminis are natural 'fake-detectors'

Because Geminis are naturally curious creatures, they thrive on observing their surroundings and learning as they go along. Their natural curiosity usually pushes them to get to the bottom of things, and if you put that curiosity together with the Geminis' innate love of knowledge, you will probably discover that Geminis have zero tolerance for posturing, pretense, or lying. 

Their passion for ferreting out the truth means they won't have any room to forgive any fakeness from you either, so be prepared to deliver nothing but the truth when you're hanging with a Gemini... even if it means being straight up with them about how much their flakiness is driving you crazy.