All that is important,is to be able to enjoy music,to treat songs with respect,and to try and perform them to the best of ones ability,this means practising them before performance.
having not led a sheltered life can help as well,as it can give the singer the ability to enter into songs, to empathise with characters,in a song,enabling the singer to really get into the song.
leading a sheltered life,is not necessarily a class phenomenon.
C Fox Smith came from an upper middle class background,but during the early 20th century,sailed on board clipper ships she overcame prejudices about her back ground,and the fact she was a woman,to write poems that have been adapted successfully as songs,please see Sailortown[words CFoxSmith tune R Miles],which is available from my website.[in my songbook Sailors dream,and also the cd Around the Harbour Town]
http://www.dickmiles.com