This is a beautiful story. I think it could be improved with a little tightening. I love the way you wove the jockey theme throughout and wish you pulled that into the into as well. You cover a lot of ground in time and emotions so you need to ruthlessly cut anything that doesn't strongly support your main theme.

I wouldn't start at the very beginning. You spend a bit too much time on content childhood you and not enough on your emotions about wanting to find this father. You list your reason for seeking him as a desire to connect with siblings but then you don't explore this dynamic at all.

There is so much good, incredibly powerful stuff in here you could split different aspects of it into many different stories. Pull some of the detail out and use if for a different story. Make sure everything is focussed on the main narrative you want to tell here.