Cis and Trans are typically opposites. In organic chemistry there are molecules which have the same chemical structure but a different orientation of atoms. Cis and Trans refer to two different ways that these can be arranged. Some clever soul probably glommed onto this and coined the phrase "Cis" referring to people who aren't "Trans". It's hyprocrisy, a way for people who don't want to be labeled to label others who have different life beliefs.