If someone can learn to speak, they can also learn to sing. Whilst there are obvious differences, there are many similarities, the most important of which is being able to hear.

A friend of mine, who is also a 'catter, is profoundly deaf but now uses a digital hearing aid.

He has always enjoyed singing, but until he got his digital aid, his attempts were a little less than tuneful. He still cannot pitch all that accurately, but the improvement continues, and is streets ahead of where he was with his analogue aid.

So it is possible that there may be a link with hearing and singing in tune (such as 'glue ear') that affects some children more than others during their formative years.

I can remember from teaching seminars many years ago that there were studies that suggested a child was more likely to naturally learn 'perfect pitch' under the age of two years of age than in later years.

In my days as a primary teacher I saw many children who had difficulty singing in tune, but learned the skill (I like to think through my help) by being allowed to join the school choir. If they weren't 'on key' for a specific event, I'd gently advise them to mime because 'they weren't ready yet'... I never ever found a 'growler' who didn't turn into a nightingale! How odd that, when I was at primary school as a pupil, I was told to shut up because I couldn't sing!

I believe that ability to sing in tune comes naturally to some, but others have to work at it. However, I also believe that too much effort can be counter-productive, if only because one's expectations are somewhat higher than one can achieve - and this applies to any instrument or activity, not just singing.

Whilst there may be a scientific explanation (or two, or three...!), I would suggest that the human mind is so capricious that there will always be exceptions to prove the rule!