Do you think it's impossible to sing if you don't have a good voice from birth? Carlos Campaña on Vox Technologies thinks [es] the opposite:

It's possible to learn how to sing without having a good voice, as the concept of “having a good voice” lacks sense when we understand that the voice is nothing else than a group of muscles working synchronized. And as we all were taught when growing up, muscles and mind can be trained.

On the same blog, Esther Justel gives us some recommendations [es] to take care of the voice.