I am sure you are right about the English influence on names beginning with Y, but the families I worked with were almost all Mexican-born and their primary language was Spanish. In addition, this "English j" sound (I don't know how to make IPA symbols appear here, or I would use them) was also used for the letter ll (as in llamar). I'm not an expert on Spanish pronunciation, but I think it is an oversimplification to say that the letters ll and y are always pronounced as IPA /j/ in every Spanish dialect.
This message was edited 4/20/2009, 2:30 PM