Dartmouth bioethicist Ronald Green told NPR there are "some very weird possibilities emerging," such as babies conceived using cells from the blood, hair, or skin cells of children, grandmothers or the deceased. Unwitting celebrities could have their cells stolen from a used soda can or hair clippings at the salon, from which egg or sperm cells could in theory be cultivated and used to conceive babies.
"A woman might want to have George Clooney's baby," Green said. "And his hairdresser could start selling his hair follicles online. So we suddenly could see many, many progeny of George Clooney without his consent."
Hank Greeley, a Stanford bioethicist, said that making human eggs and sperm from stem cells "opens up an enormous number of possibilities for changing how humans reproduce."
Brehany said Catholic teaching holds that the "greatest goods" of human persons, like marriage, marital love, and procreation, must be "treated with the greatest respect."
"How we respect such goods is a matter of significant principle," he said. "Once we violate or misuse them, then it is harder to treat them as they deserve, and the negative impacts on the innocent human beings are immense."
Brehany cited the 1987 Congregation for the Doctrine of the Faith document Donum vitae, which criticizes the separation of the desire to procreate from the conjugal act between married spouses. He suggested that such a violation results in decreased respect for "the dignity of the human persons brought into being this way" and for their suffering "as they struggle to know their own identity and dignity."
The 2008 CDF document Dignitas personae also addresses bioethical questions related to human life and procreation. It said: "The origin of human life has its authentic context in marriage and in the family, where it is generated through an act which expresses the reciprocal love between a man and a woman… human procreation is a personal act of a husband and wife, which is not capable of substitution."
While recognizing the legitimacy of the desire for a child, and voicing understanding for the suffering of infertile couples, the document adds "such a desire, however, should not override the dignity of every human life to the point of absolute supremacy."
Kevin J. Jones is a senior staff writer with Catholic News Agency. He was a recipient of a 2014 Catholic Relief Services' Egan Journalism Fellowship.