Bravo to the parent who sings to their child! That is more important for producing a singing child than anything I can think of. Young children learn more from their parents than elsewhere, so they are learning that singing is a normal and joyful activity and they are picking up all sorts of good vibes about it.
Would anyone dare NOT to read to their child because they don't have a "Charleton Heston" resonant voice? Absolutely NOT!
Would anyone dare NOT to cook a family Thanksgiving dinner just becuase they were not Julia Child? Absolutely NOT!
Memories are made, enjoyed, and treasured more because of who is involved.
What's that saying? "How silent the forest would be if no birds sang except for the best."
Yea to the child that hears a parent singing!