(CNN) -- Choosing the sex of a child may be a very real possibility, according to researchers. But like cloning and genetic engineering, the procedure is spawning controversy and ethical questions.

The procedure by researchers at Genetics & IVF Institute separates sperm cells by female X chromosomes, or male Y chromosomes, before artificial insemination. The Institute says the technique is 93 percent effective.

Some say the process could prevent same-sex hereditary diseases and appease families wanting children of both sexes.

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"In this case, science is doing something that can have some manifest human good," said Lawrence Gostin, professor of law and public health at Georgetown University. "It can prevent disease and also it can promote family and human happiness."

But concerns persist. The ability to choose a child's sex could potentially be used in societies where one sex, usually male, is preferred over another.

"What is does is really reinforce the social and economic inequalities in the world," Gostin said.

Dr. Jamie Grifo, director of reproductive endocrinology at New York University Medical School, has been using another technique to pick the gender of an embryo. He said the school only uses its procedure to prevent diseases that are passed along in genes to only one sex, such as hemophilia in males.

"They're doing very important research, but it's a matter of what they're using if for that worries me," Grifo said. "I don't think we should be doing sex selection."

Some health experts say the process is still not proven and its safety is unknown.

"It's really a series of anecdotes," said Dr. Robert Stillman, a board member of the American Society for Reproductive Medicine. "A bigger study might put this in the wastebasket where many other attempts at sex selection have gone."

The Associated Press contributed to this report.