Answer:
Genes, Duplication, Similar, Close together
Step-by-step explanation:
There are two main families of genes coding for the alpha globins and the beta globins. Evidence that these gene families are formed by duplication of ancestral genes includes that these genes have similar nucleotide sequences, and that they occur close together on chromosomes 11 and 16.
It is believed that the present gene families comprising the human haemoglobin are formed through the duplication and then divergence of the ancestral genes giving rise to families of gene clusters that are similar but not identical in nucleotide sequences.