Can embryo selection ruin our genetic coding?
In a way, it can…at least for mammals. To do embryo selection in mammals, you have to perform the selection in embryonic culture conditions. That means you have to take the embryos out of the mother, perform the selection, and put some of them back in. This temporarily disrupts the normal environment experienced by the embryo and is known to cause changes in gene methylation. (Almost) every cell in your body has a complete genome, but each cell type expresses a different combination of genes. For example, your neurons don’t express muscle proteins, and vice versa. One of the ways that a cell “knows” which genes not to express is through gene methylation. A cell adds methyl (-CH3) groups to cytosines near a gene that it plans to permanently turn off in itself and all of its descendants. This helps the cell to go from being pluripotent (capable of adopting many fates) to being differentiated into a single cell type. An early embryo is like a ball of pluripotent stem cells. If you mess
