Depending on what trait the alleles carry, the brothers will have a different phenotype and a different genotype.
For example; Eye color. My sister is heterozygous, meaning she has brown eyes. I am homozygous recessive, meaning I have blue(green/hazel) eyes. We both have the same parents, I just happened to inherit both of the recessive eye color alleles from my parents whereas, my sister inherited both the dominant and recessive alleles.
So, since the brothers inherited different sets of alleles, their genotype for a certain trait will be different.
In biology, a gene is a basic unit of heredity and a sequence of nucleotides in DNA or RNA that encodes the synthesis of a gene product, either RNA or protein.
They both have similar environments, which show they have evolved similar behaviors and appearances. hope this helps <3
we need a graph to do this can u provide a picture?