yes, you can become Wiccan just as you can become Christian, Jewish, or any other faith. Wicca is a religion. I was born into a Wiccan household, but I was not a "born Wiccan" since Wiccans believe you must choose your own religious path. It is recommend you study before converting, and certain paths like British Traditional Wicca would require you to train under and be initiated by a coven of practising British Traditional Wiccans. Many individuals simply pick up a book and start calling themselves Wiccan. This is fine, but you should put more into it than that since Wicca is an actual religion and not a fashion statement.