Scientists make clones by removing the DNA from an egg cell and replacing it with DNA from the cell of an adult. The cloning process appears to reset the adult's genetic code so that it can execute the developmental program of an embryo, but that transformation may not be perfect in all cases. Some scientists believe the embryonic clone may use, or "express," its genes in ways that could affect the clone's health when it grows up.
Suspicious creature that I am, my first thought upon reading this was: "which scientists?"
Scientists representing the other side get mentioned by name. Why not these "some" scientists?