Answer:
A number of natural fats contain double bonds. Adding hydrogen to those bonds changes them to single bonds. That raises the temperature at which the fat will burn during the cooking process.
When nature hydrogenates fat, it always produces cis fat. It never produces trans fat. Trans fat does not appear in nature. It does appear in cattle fed in feed lots. Feed lots do not appear in nature. Companies can add hydrogen to fat and produce either cis or trans fat. The technology exists to produce either. It has been around for years.