(EXPLANATION)They have been charged by contacting while they rub against others, and therefore, are attracted to clothing that is neutral or has an opposite charge.
In laundry terms, static cling is the result of an electric charge build-up due to a fabric brushing up against one another which occurs during the tumble-drying process. Static cling is more prevalent during winter because of the dry air. Luckily, there are some ways to get rid of static on clothes from the get-go