I would say no because not all DNA is the same so some may respond differently
I believe he is looking for an allele
An allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosomes. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.
He chose to study birds, plants, and animals. Mostly 2 types of Finches.
C) Crops may cause an increase of allergic reactions in humans.