After decades of research in genetics, tremendous progress has been made in our ability to read the DNA of embryos, paving the way for the birth of healthier humans through the eradication of some horrific genetic diseases even before a baby is born.But could scientists allow parents to pre-screen their embryos for specific, desirable traits – blue eyes, blond hair, high IQ, tall or thin physique? Could scientists soon allow parents to select the generic characteristics of their offspring? According to a release by the Hebrew University of Jerusalem, today selecting embryos for eye color or sex are easy feats for a scientist to perform, as they require only one or very few genes. However, when it comes to selecting for traits that involve numerous genes, such as height or IQ, according to research by the Hebrew University, scientists are not quite there. A team from HU, led by Dr. Shai Carmi of the Braun School of Public Health, report that current embryo selections based on height or IQ have only modest benefits. Carmi said that although in the past five years selecting embryos for particular traits has become easier and cheaper and can help parents with serious genetic diseases, “it is still a highly controversial procedure when it’s used for non-life-threatening reasons where ethical questions of eugenics and unequal opportunities arise.”The research comes one year after a geneticist in China modified the DNA of human embryos. It was considered a watershed moment in biotech history but was wrought with ethical controversy.Carmi’s experiment may explain why.Carmi’s team evaluated what would happen if scientists took 10 embryos from one pair of parents, rated each embryo for height or IQ, and implanted the embryo with the highest score. They ran computer simulations using gene sequences from real people to create profiles of hypothetical embryos that would result from pairings of those people and predicted the adult height or IQ for each of the embryos based on the gene variants present in their genomes.First, the results were less bold than one might expect.For height, the gain was three centimeters above the average embryo in the batch and for IQ, the gain was three points.Furthermore, Carmi explained, not only was the desired outcome – increased height or higher IQ not guaranteed and not drastically improved – potential pitfalls were identified, too. One may select for the improvement of one outcome, but increase the risk of another, less-desirable outcome, although the researchers did not examine this possibility.For example, the group of genes that is linked to a high IQ is also somewhat linked to anorexia, according to published studies.Additionally, selecting for several traits at once – smart or tall and thin – will result in lower gains for each trait.To corroborate their findings, the researchers also used real-world data to demonstrate that trait predictions based on currently known gene variants are not guaranteed. They examined the genetics of 28 families with 10 or more adult-age children. They selected those children with the top score for height based on their genomic makeup. However, in three-quarters of the families, the scientists found that the child with the genomic data that was supposed to be tallest was not the tallest sibling.“Our current knowledge of the genetic makeup of certain traits may not be enough to generate a substantial increase in the desired traits in an embryo selection scenario,” Carmi explained. “The crucial roles of nurture and unknown genetic factors are also at play.”The research was published in the latest edition of the journal Cell.