Everybody on Earth is related by virtue of the fact that we're all the distant grandchildren of the very first humans. Exactly when these grandparents were alive is up for discussion, but scientists think it was probably somewhere between 550,000 and 750,000 years ago. The first humans had children and they became brothers and sisters, who made way for aunts, uncles, nieces, nephews and, most confusingly, cousins.
The word "cousin" is often used loosely across cultures, and even throughout American history.
"Sometimes aunts or uncles have been called cousins, and the word cousin has also been used in a general way to refer to any relative," says Jenifer Kahn Bakkala, a genealogical researcher and writer who sits on the board of directors of the Association of Professional Genealogists. "Another word used historically is 'kinsman' or 'kinswoman,' which refers to a person with any sort of familial relationship to the subject, especially a relationship that is complex or undefined."
However, the modern cousin relationship is the one used most often to describe the genetic proximity between two people who are contemporaries or near contemporaries. But since you're related — albeit very distantly — to everybody you see in the airport, describing a distant familial relationship between two people can get complicated. We have first, second and third cousins, we have cousins once removed, we have half cousins. We even have kissing cousins. But what does it all mean?