Yes I read in Latha's upahara book, that even Dharmadasa Walpola could not identify his son's voice. When a song by his son was played on the radio, Dharmadasa has called his wife & said,
මම ඔය වගේ ගීතයක් ගායනා කෙරුවෙ නැහැනෙ ?
පුතාගෙ හඬ තමාගෙ හඬ කියා පියා පවා රැවටුනා.
:):):):):):):):):)