Cloning creates controversy for several reasons, broadly categorized as concern for human safety and concern over improper or unethical animal treatment. Cloning draws resistance from some for altering biological processes to enhance or create certain features, such as a brighter color, larger size or softer fur. Some argue these changes conflict with biological norms, and pose risks of disease and illness for humans and other animals exposed to the genetically altered organisms.
Cloning draws criticism in the context of animal and plant replication, and invites even more criticism when applied to humans. While some researchers and scientists praise cloning for eradicating certain diseases and facilitating immunization, others cite disease resistance and development of new allergies as counterpoints. Some researchers, for instance, believe drinking milk of cloned animals, fortified with nutrients and antibiotics, might control the spread of illness in impoverished areas, proving more effective and less expensive than traditional vaccinations.
Others, such as animal welfare advocates, caution those moves as experimental and not founded on years' worth of scientific studies, which raises questions of safety. Cloning has criticism among some biologists over concerns that artificial gene selection and replacement ultimately changes some species, putting them at risk for mutations, defects and even extinction, as genetic variation decreases over time.