Wild-type is the term geneticists use to refer to non-mutants.
It literally means organisms that are the same, genetically, as
those in the wild, compared to ones that have been grown under
coddled conditions in the lab for generations, going soft in the
absence of natural selection, or that are specifically mutant at
some gene or other. There are no wild-type humans. Well, maybe
there are a few, somewhere, but even they are not really non-
mutants. We all carry millions of mutations in our genome –
positions where the sequence in our genome differs from the
typical sequence. Where everyone else has a “T”, you might have
an “A”, for example. Most of these mutations have no consequence
– they are simply neutral variation in DNA that has no
discernible function. It turns out that most of the genome is
not made of genes – the bits of DNA that code for proteins
actually comprise only about 2-3% of the total sequence.
Mutations that change the code for proteins are by far the most
likely to cause disease or to resu