When Julie Veilleux discovered she was American, she went to the nearest U.S. embassy to renounce her citizenship. Having lived in Canada since she was a young child, the 48-year-old had no idea she carried the burden of dual citizenship. But the renunciation will not clear away the past 10 years of penalties with the Internal Revenue Service (IRS).Born to American parents living in Canada, Kerry Knoll’s two teenaged daughters had no clue they became dual citizens at birth. (An American parent confers such status on Canadian-born children.) Now the IRS wants to grab at money they earned in Canada...