uses
  TlHelp32, Contnrs;

type
  TProcInfoItem = class
  private
    Fth32ProcessID: cardinal;
    FParentExeName: AnsiString;
  public
    property Th32ProcessID: cardinal read Fth32ProcessID write Fth32ProcessID;
    property ParentExeName: AnsiString read FParentExeName write FParentExeName;
end;

function TForm1.GetParentProcessExeName: AnsiString;
var
  hProcSnap: THandle;
  Proc32: TProcessEntry32;
  i: integer;
  ProcInfoList: TObjectList;
  ProcItem: TProcInfoItem;
  CurrentProcId: Cardinal;
begin
  Result:= '';
  CurrentProcId:= GetCurrentProcessId;
  ProcInfoList:= TObjectList.Create;
  try
    hProcSnap := CreateToolHelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    if (hProcSnap > 0) and (hProcSnap <> INVALID_HANDLE_VALUE) then
      try
        ZeroMemory(@Proc32, SizeOf(TProcessEntry32));
        Proc32.dwSize := SizeOf(TProcessEntry32);
        if Process32First(hProcSnap, Proc32) then
          repeat
            ProcItem:= TProcInfoItem.Create;
            ProcItem.Th32ProcessID:= Proc32.th32ProcessID;
            ProcItem.ParentExeName:= ExtractFileName(Proc32.szExeFile);
            ProcInfoList.Add(ProcItem);
          until not Process32Next(hProcSnap, Proc32) or (CurrentProcId= Proc32.th32ProcessID);
      finally
        CloseHandle(hProcSnap);
      end;
      
    for i:= ProcInfoList.Count- 1 downto 0 do
      if TProcInfoItem(ProcInfoList.Items[i]).th32ProcessID= Proc32.th32ParentProcessID then
      begin
        Result:= TProcInfoItem(ProcInfoList.Items[i]).ParentExeName;
        break;
      end;
  finally
    ProcInfoList.Free;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ShowMessage(GetParentProcessExeName);
end;