Names that can be used for either male or female are called unisex names. Examples of which are Sam, Alex, and Kris. These names are most often used as nicknames from Samuel for male or Samantha for female, Alexander for male or Alexandra for female, and Kristopher for male or Kristina for female, respectively.
Some parents name their babies after the place where they were conceived, born or their favorite place to go to. Examples of which are Alabama, Brooklyn, Dallas, Paris, Montana and a lot more. Another reason why parents choose to give their baby a unisex name is so that they can still use the name whether their baby is a boy or a girl. However, in some cases, they just simply love the name itself and it so happens to be unisex.
The bad thing about having a unisex name is that the person may get offended or laughed at when mistaken to have the wrong gender. This happens especially during the childhood stage, when kids normally laugh at other children for having unisex names because they are too immature to understand the thought of having a unisex name.
Nowadays, however, some names that were suitable for both male and female have become related mostly to just one gender. Paris, Leslie, Cameron and Erin, were once used as unisex names, but now they are more associated to females. At the same time, Alex, Adrian, Sam, and Taylor are now mostly used for males. Recently, most unisex names are now associated to females rather than to males.