We just found out that he likes Bach pretty much. I say pretty much because of course he doesn’t have yet sense of what he likes or doesn’t like —even less musically speaking— but seems that Bach usually calm him down and makes him sleep. I doubt that the reason is because the music is really boring for him, but probably the harmony of rhythm of the music make him calmer, like to any other human.
We tried first with the Cantata BWV 11 —known as Praise God in His Kingdoms— specially the chorus (towards the end) .
Also with the Brandenburg Concerto No. 3.
And to even my surprise he liked —felt asleep with— the Toccata and Fugue in D Minor.
We are looking forward to try more music with him, classical and modern. We are in Finland 
so heavy metal is pretty much encourage.
Although I really think we’ll begin with something Nordic, but more soft, like Sigur Ros.
Let’s see how he develop his musical ear and taste. What is pretty clear for me is that he doesn’t going to be smarter or dumber because he decides to listen to one kind of music or other, or just because we play him some kind of music. However, I really believe that we are cultural animals and we end up being whatever we are exposed to in our environment, for good or for bad. So, better start with the good stuff early on.