Who is The Opposite Gender?

Sam, Alex, Charlie, and Jordan are related. 

One of them is the opposite gender from the other three. Here are some facts:

1. Charlie's only son is either Sam or Alex.

2. Jordan's sister is either Alex or Charlie.

3. Jordan is either Sam's brother or Sam's only daughter.

Who is the opposite gender from the other three?

Know here the name of the person with opposite gender!