Meet Mito and Tracker (above). Along with Spindler and Spindly, the baby monkeys were created by scientists using the egg of a mother, the sperm of a father and the mitochondrial DNA of a third 'parent.' The successful creation of these monkeys could potentially lead to the end of inherited genetic disorders. So why do some have their panties in a bundle? One concern is that it could violate "a long-standing taboo against tinkering with the "germline" because of the chance of unforeseen consequences. Some experts worry, too, that germline genetic manipulation would give rise to a market in expensive elective genetic enhancements."
Ok...unforeseen consequences, that's what research is for. Elective genetic enhancements...I agree, that is a slippery slope, but then there is this argument:
"If the mitochondria donor (who is probably a young woman) is later infertile, she might seek visitation to the child, After all, people didn't think surrogate mothers, who are not the nucleic DNA donors, would want access to the couples' genetic child, but some have gone to the courts for such access."