For me, I always identified as poly - though closetly so. I always knew I had the capacity and desire to love more than one person, and be with more than one partner at a time - but never actually thought it was a potential reality. My husband and I have known eachother since we were 6, I always knew I would marry him. I did. 2 years after we got married I met A. Within months I knew I liked her, within a year I was deeply in love with her - and was so conflicted about the whole thing. It was my husband and her opening up their relationship, sexually, that dove me into practicing polyamory.
Even though I identified with it, and wanted it - I still struggled quite a bit at the beginning. But im glad I stuck with it, and worked through my feelings.