I’m attracted to my son’s older half brother

My (52f) son (31) is from my first marriage. His father already had a son from his first marriage, let’s call him M (41-ish). M was here last year to visit family and I felt a deep attraction to him and I felt the same from him, but chose to ignore it because of the family ties. My question is, would it be wrong or creepy to be interested in seeing where it goes or if there’s anything there?