The captain of Germany\'s national football team Philipp Lahm is not the first sportsman to write a book. But he is one of a few who have done so while still playing. And he has stirred up quite a storm with his critique of German football greats like Rudi Voeller and Juergen Klinsmann which has angered German football officials and national team coach Joachim Loew. \"A Subtle Difference,\" is the Bayern Munich star\'s first book. Lahm says he is not gay, describing his marriage to Claudia as genuine and not for \"appearances\". He denies living in Cologne with another friend. He does caution other footballers though against coming out. For several days the claims and revelations have been hotly discussed around Germany - particularly his criticism of some players on the German national team, including picks made by current coach Joachim Loew. Lahm has apologized for the criticisms and Germany\'s national football association has indicated that he will remain captain, a position he was handed in 2010 where he led the side to a third-place finish at the World Cup in South Africa.