Why is Christian tradition so silent regarding John the Baptist? From the New Testament, all we know is that he (supposedly) was a Jewish ascetic and preacher who was born miraculously, who taught that the Messiah was soon to come, who practiced baptism and baptized Jesus, and who was executed under Herod.
Any other information comes either from Islamic or Mandaean sources, both of which are of dubious authenticity. There is also some stuff from Josephus, but it's basically the same as what is in the New Testament.