Here's a link to an interactive database that queries transportation/penal records for an extended period in Ireland      (including the 1840s).   While many insert surnames for their search, you might also query the Db using common words like "oatmeal" or "bread". The myth elements lift as the screen scrolls the names and the places of the mothers and sons. Apparantly the ruling class kept excellent records:

http://www.nationalarchives.ie/topics/transportation/transp1.htm