Final answer:
The major controversy surrounding stem cells is the ethical and legal issues associated with embryonic stem cells, which are sourced from the destruction of embryos. This contrasts with less controversial adult stem cells and induced pluripotent stem cells. The debate involves a myriad of interest groups with varying views on the future and regulation of stem cell research.
Step-by-step explanation:
The major controversial reason confronting the use of stem cells that has limited their use is the ethical dilemma associated with embryonic stem cells. Embryonic stem cells have the potential to differentiate into nearly every type of cell, but the process to obtain them involves the destruction of embryos, which raises ethical and legal questions. This is starkly opposed to adult stem cells and induced pluripotent stem cells that do not come with the same ethical baggage but have a more limited range of differentiation.
Issues around stem cell research have led to increased lobbying and interest groups both for and against it. As society's attitudes continue to evolve and new technologies emerge, these debates are likely to become even more pronounced. In response to ethical concerns, there has been a call for definitive guidelines to manage the evolution and use of such medical biotechnologies.
Furthermore, while some bioethicists argue that concerns over eugenics and abuse of stem cell technologies are overstated—believing those procedures will remain expensive and rare—others contend that the pace of technological advancement may lead to unforeseen challenges, including those that have to do with cost, accessibility, and the potential for regulation.