Charlie is The Opposite Gender!

What was the puzzle?

Given Facts : 

Sam, Alex, Charlie, and Jordan are related


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.

ANALYSIS : 

1] As per (3), if Jordan is Sam's only daughter then Jordan must not have any sister. But this is opposite to the fact (2). Therefore, Jordan must be Sam's brother. Jordan is male for sure. 

2] If Jordan's sister is Alex (female), then as per (1), Charlie's only son (male) must be Sam. But as concluded above [1], Jordan is Sam's brother so how Charlie can have only one son? Therefore, Jordan's sister is Charlie who is obviously female.

3] If Jordan is Sam's brother [1] and Charlie is Jordan's sister then it's clear that Jordan, Sam and Charlie are siblings. And now as fact (1) suggests Charlie's only son must be Alex (male).

CONCLUSION : 

ALEX, JORDAN and SAM are male and CHARLIE is the opposite gender i.e. female.