Final answer:
Goats and sheep are able to share genetic material for gene substitution due to their common genetics, making them compatible for creating transgenic animals.
Step-by-step explanation:
Scientists have been able to substitute defective parts of a goat’s DNA with genes from sheep because goats and sheep share common genetic material. This genetic similarity allows for the creation of transgenic animals, which are organisms that have been genetically modified to express recombinant DNA from a different species. It is the shared genetic material between these species that makes such genetic engineering possible. Goats and sheep do not belong to the same species, nor do they possess identical DNA sequences. They do, however, exhibit similar physical characteristics due to their close genetic relationship as members of the same family, Bovidae.