The story is much more complicated and deeper than it seems at first.
SPOILERS!!!1!
Basically you come to your mother's birth country to spread her ashes next to 'Ishwari'. That's your dead sister. Your father killed her, because she was daughter of Pagan Min, king of Kyrat. That makes Pagan your step father.
Of course, that broke Pagan, turning him into cold-hearted dictator murderer.
After he organizes a meal just for you and TELLS YOU TO WAIT AT THE DAMN TABLE, you escape, join The Golden Path (founded by your father) and do more bloodshed than Pagan did. Lol.
Then you can choose to support either of two Golden Path leaders: Amita or Sabal
Amita - feministic and egoistic self-assured b*tch that doesn't take 'no' for an answer. Also drugs advocate and potential smuggler. If you choose her, she recruits children for soldiers at the end of the game.
Sabal - close-minded culture zealot which favors marriage of young girls and some nasty traditional rituals. Zero respect for women. If you choose him, he turns a young girl into some form of godess or something. He also slits throats of Amita-supporting soldiers.
FYI Choosing Pagan, or yourself would ironicaly be the best option. Sadly, you can't do that.