They can be but not always. Obviously if you have someone who is musically talented in the family, that goes a long way.
On the other hand if you are interested in music and get all the support & encouragement from your peers, whether it is at school or home any thing can be acheived.
Like Deepak says some are already gifted from God.
I wonder how many there are that have this gift and have never been fortunate to follow it or even realise they have it?