Could you site the studies that this section was based on. I would be interested in reading further as this seems to be the sticking point for most people when it comes to the topic of GM for embryos.
This is one of the better papers I know of examining sibling validation. To quote from the article:
Sibling comparisons are a powerful method with which to validate genomic prediction in humans. Siblings (i.e., children who share the same mother and father) have typically experienced similar environments while growing up: family social status, exposure to toxins, diet, climate, etc. all tend to be similar3,4. Furthermore, siblings are concordant for ancestry and display negligible differences in population structure.
If environmental conditions in a specific region, such as, e.g., Northern England, affect disease risk, the predictor trained on UK data might assign nonzero effect sizes to SNPs associated with ancestries found in that region—i.e., the predictor learns to use population structure correlated to environmental conditions. These specific SNPs are correlated to disease risk for environmental reasons, but might not have any connection to genetic mechanisms related to the disease. They likely have little power to differentiate between siblings, who experienced similar family conditions and have have identical ancestry.
It is also possible that some SNP variants affect nurture (the way that parents raise their children). These SNPs could affect the child phenotype via an environmental mechanism under parental control, not a biochemical pathway within the child. This is sometimes referred to as a genetic nurture effect9,10,11,12,13. Note, siblings raised together would both be affected by parental genetic nurture variants, so these effects are weakened in family designs.
Sibling comparisons reduce the impact of factors such as those described above. We expect some reduction in power when predictors trained in a population of non-sibling individuals are tested among sibs. Sibling validation likely yields a better estimate of truly causal genetic effects. A more complicated measure of familial relatedness might lead to even better results14, but we restrict our analyses here to siblings.
There’s more in the paper if you care to take a look.
Could you site the studies that this section was based on. I would be interested in reading further as this seems to be the sticking point for most people when it comes to the topic of GM for embryos.
https://www.nature.com/articles/s41598-020-69927-7
This is one of the better papers I know of examining sibling validation. To quote from the article:
There’s more in the paper if you care to take a look.