I think the story could have used more fleshing out. An exploration of motives for the father. Maybe the for us readers to understand what is happening and have time to digest it.

I think you should build a bigger, longer story based on this. Because it seems the father could use more background to how he is so understanding of such an odd condition other than just being a father. Otherwise, much like what @theinkwell said, it seems like the father gave the son a pass to murder. I can how you tried to avoid that with the last paragraph but you need to remember that the son didn't pay for his crime.

I hope this isn't harsh, but I am really a fan or your writings. So this comes from a place of love and admiration.