In Europe, though, genetically modified crops are taboo. Cloning human embryos for research has been legally supported in England and several other countries, but it is banned in more than a dozen others, including France and Germany.

In North and South America, genetically altered crops are widely used. But embryo cloning for research has been banned in most countries, including Brazil, Canada and Mexico. It has not been banned nationally in the United States, but the research is ineligible for federal financing, and some states have outlawed it.

Dr. Silver explains these patterns by dividing spiritual believers into three broad categories. The first, traditional Christians, predominate in the Western Hemisphere and some European countries. The second, which he calls post-Christians, are concentrated in other European countries and parts of North America, especially along the coasts. The third group are followers of Eastern religions.

“Most people in Hindu and Buddhist countries,” Dr. Silver says, “have a root tradition in which there is no single creator God. Instead, there may be no gods or many gods, and there is no master plan for the universe. Instead, spirits are eternal and individual virtue — karma — determines what happens to your spirit in your next life. With some exceptions, this view generally allows the acceptance of both embryo research to support life and genetically modified crops.”

By contrast, in the Judeo-Christian tradition, God is the master creator who gives out new souls to each individual human being and gives humans “dominion” over soul-less plants and animals. To traditional Christians who consider an embryo to be a human being with a soul, it is wrong for scientists to use cloning to create human embryos or to destroy embryos in the course of research.

But there is no such taboo against humans’ applying cloning and genetic engineering to “lower” animals and plants. As a result, Dr. Silver says, cloned animals and genetically modified crops have not become a source of major controversy for traditional Christians. Post-Christians are more worried about the flora and fauna.

“Many Europeans, as well as leftists in America,” Dr. Silver says, “have rejected the traditional Christian God and replaced it with a post-Christian goddess of Mother Nature and a modified Christian eschatology. It isn’t a coherent belief system. It might or might not incorporate New Age thinking. But deep down, there’s a view that humans shouldn’t be tampering with the natural world.”