If sex is such a natural phenomenon, how come there are so many books on How To?

If sex is such a natural phenomenon, how come there are so many books on How To?

<center><br><a href="http://www.sisodia.in"><img src="https://lh3.googleusercontent.com/-vehTkW32ibA/Tx1xqKMllcI/AAAAAAAAGh0/zJGHVwbVZf0/s0/If%252520sex%252520is%252520such%252520a%252520natural%252520phenomenon%252520%252520how%252520come%252520there%252520are%252520so%252520many%252520books%252520on%252520How%252520To.jpg"></a></center>