Nature generally doesn't care whether it
makes a left- or right-handed molecule.
If you make a bunch of amino acids in
a lab experiment, you'll more or less end
up with the same number of left- and right-handed
molecules. There is no preferred state in
nature for one or the other.
A racemic mixture is one that has equal
numbers of left- and right-handed molecules.
It's pretty interesting, then, that
all of life's amino acids are L-amino
acids (left-handed).
And most biologically important
carbohydrates are right-handed.