I don't know where you got your numbers. But humans have between 300-600 point mutations per person per generation. Add to that all the other types of mutations and you have more then ''two three novel mutations ... not present in our parents''.
I'm pretty sure you're out by a factor of about 100 on these numbers.
They all make glycine. So what is the effect of a point mutation changing GGA to GGU?
The tRNAs needed to translate GGA to glycine or GGU to glycine exist in differing quantities; altering the code can alter the expression rate of proteins.