When I was about 13, I had my first sexual thoughts about my dad. I had never seen him naked before, and one day, while he was showering and no one else was home, I decided that I would peek through the skeleton-key-hole of the bathroom door and see what he looked like when he came out of the shower.
When he came out of the shower, he stood naked in front of the sink, directly in front of my line of site. Dad was older, already in his early 50s, but that did not make him less attractive. I enjoyed looking at his ass, which was still in good shape, and his average-sized dick which was just like mine.
I loved seeing the pubic hair and especially liked looking at his low hanging balls. I jacked-off in my pants and came all inside my underwear. My heart was racing and I ended up doing it again, about five more times or so over the next few years.