According to Sanatana Dharma (eternal occupation of the soul), all living entities have a free-will. At the same time, they are perfectly controlled at all times by the laws of God. One may say, how is that possible?
Suppose, there is a fire. One can knowingly or even unknowingly put his hand in that flame. This action is his free-will. God has given us the intelligence and discretion to tell right from wrong, good from bad. So He will not interfere with our free-will or our action. But at the same time, in accordance to the laws of God, one has to accept the reaction of that action - his hand will get burnt.
In this way, a living entity is continuously exercising his free-will to make new choices. At the same time he is enjoying/suffering the consequences of his earlier choices made using his free-will.
The birth of a living entity in different cultures, with different genetic make-up, different environments etc. is simply an arrangement of God to give that individual a faciity to enjoy/suffer the consequences of his different free-will choices made over many lifetimes. That is why someone is born rich, others not so rich; someone is handsome while another not so handsome, someone intelligent another not. All are enjoying/suffering reactions of their free-will choices made over many previous lifetimes.
Scientifically put - Every action (using free-will) has an equal and opposite reaction.
Religiously said - What you sow, so shall you reap