Both of my children are musicians, my son 10 (piano) and my daughter 13 (piano and violin). Both enjoy classical music as well as jazz and 60's-80's rock. Neither one cares for current day pop or rock. So as others have mentioned I believe a childs musical taste is to a great degree influenced by what their parents like as this is what my wife and I listen too as well. Of course peer pressure (friends) are very strong as well but neither has given into this influence yet but we shall see.
Chuck
Chuck