Is it normal to like your step brother?

When i was 8 my mom remarried to a man who had kids already. One of his children happens to be my age. At first, we hated each other. However, as the years passed on their started to be secret flirtation between us. It started as a love hate relationship. We would pretend to be "mean" to each other, but then start texting each other at night. We didn't live with each other for any of those years because he lives in a different city. I see him maybe once a month when he comes to stay with us for the weekend.
There has always been something between us, and finally a couple months ago we started becoming even closer. Some stuff happened between us (I don't think I should go into details) but our parents started becoming suspicious.
After that he told me that we shouldn't do anything like it anymore. However, a couple weeks later he started doing the exact same things again.
After knowing him for a lot of years, I have started to become really attached to him. The problem is I don't know if he feels the same way?
I want to stop liking him, but I don't think I can. My feelings are too strong.
Is this normal?