A group of researchers at the Hebrew University of Jerusalem has shattered the notion that prospective parents will be able to order up babies with an Einstein IQ and as the height of a pro basketball player, saying that in selecting embryos for these two traits, the impact is not very big.
Ever since doctors began performing in vitro fertilization to help couples have children, they have been screening embryos for genetic disorders, setting the stage for the fantasy of “designer babies.”
These days, scientists can easily select embryos according to their eye color or sex, as these traits involve one or just a few genes, the scientists said. But how easy is it to boost babies’ IQ or height?
Led by Dr. Shai Carmi, the researchers at the Hebrew University of Jerusalem’s Braun School of Public Health decided to see how feasible it is to select embryos according to these two parameters.
Their study found that by using current embryo selection techniques, based on height or IQ, the results “have only modest benefits”: for height, the scientists found an increase of two to three centimeters (0.8-1.18 inches), and for IQ, an increase of two to three points.
“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 said. “The crucial roles of nurture and unknown genetic factors are also at play.”
The findings were published in the latest edition of the journal Cell.
“In the past five years, selecting embryos for particular traits has become easier and cheaper,” said Carmi in a statement issued by the Hebrew University. “While this technique is a tremendous help to 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.”
Carmi’s team ran virtual experiments based on real-life genomic data to answer the question: What would happen if we took 10 embryos from one pair of parents, rated each embryo for height or IQ, and implanted embryos 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. They predicted the adult height and IQ for each of the embryos based on the gene variants present in their genomes.
What they found in their study is that the expected advantages for the “top scoring embryos” were relatively small. For height, the gain was 3 centimeters above the average embryo in the batch and for IQ, the gain was 3 points. With five embryos to choose from, the gain was 2.5 centimeters and 2.5 IQ points. When the team widened the scope to see what would happen if they could choose from a batch of 50 embryos — a near-impossible biological feat for most couples — the highest gain was 4.5 centimeters for height and 4.5 IQ points.
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 looked at the genetics of 28 families with 10 or more adult-age children. Based on the genomic makeup of each child, they selected those with the top score for height. However, in 75% of the families, the child that the scientists had “selected” was not the tallest sibling, even though their genomic data had predicted that they would be.
For those who may believe that even three centimeters of added height or a 3-point IQ boost may be worth the effort, Carmi issued a warning: in embryo selection, not only are desired outcomes not guaranteed, but there are also pitfalls involved in such a procedure.
Because of the nature of gene variants, he explained, sometimes the selection of an embryo for one outcome increases the risk of another, less-desirable outcome.
For example, the group of genes that is linked to a high IQ is also somewhat linked to anorexia. Also, attempts to select for several traits at once — say, an embryo that is tall and smart and thin — would make the process far more complicated, because an embryo that ranked highest for IQ may rank lowest for the desired body mass index (BMI), he said.