If something in nature occurs, then it cannot, by definition, be unnatural. It can be common, unusual, bad, illegal etc but not unnatural. If you take what some people say about homosexuality being unnatural to its logical conclusion, then people who are ill should not be cured, operations should not be performed to remove your appendix, blood transfusions should not be given etc.
Of course we all know that there are some religious groups who think in this way. I have no patience with them.