I have never met a natural-born negotiator. The best negotiators I've met have been self-made, not manufactured by their parents. People can adapt and improve with conscious effort, and, in fact, that is the only path to becoming a good negotiator.
Nevertheless, a great number of people believe successful negotiation is all in the DNA, and that negotiation, like leadership, is something you're born with.
You don't have to travel far to see that the right kind of experience can dramatically improve your negotiation outcomes. The "magic bullet," when it comes to experiences that enhance negotiation skills, is the I-C-E rule.