Apparently they are not mutations or defects? But variations.
The technical term is polymorphisms, which puts the "P" in SNP. But "variant" seems to work better for us as laymen.
These polymorphisms are all technically mutations, because they represent changes in the DNA. People assume mutations are meaningful, but most mutations have no impact at all, and are completely normal. So they are definitely not defects.
Missense mutations and nonsense mutations occur in the exons (coding sections of genes) and do have an impact on the enzyme the gene produces in the body. Missense mutations occur when one amino acid is swapped with another. Sometimes the enzyme functions the same, but sometimes function is drastically altered. Nonsense mutations mean that the gene terminates the enzyme prematurely, which is usually quite significant, but sometimes isn't if it happens near the end of the gene.
SNPs in non-coding sections and in between genes shouldn't have an impact. If they do (outside of splicing sequences and similar), there really isn't an explanation for it. But genetic studies correlating SNPs with disease, personality traits, or symptoms, tend to have a lot of false positives, and correlations involving non-coding and intragenic SNPs are especially suspicious. They also aways have very small effect sizes, even if supposedly statistically significant, which doesn't help
I think Promethease includes effect size, or at least research links, but all other SNP-interpretation services completely fail to distinguish between serious mutations and irrelevant SNPs which have very little impact if they have any at all.
So if the gene pool they (SelfDecode) are referencing are of European decent, how would it impact those of other races?
Ethnicity shouldn't make a difference. But it doesn't make sense to use European reference samples when there are huge international samples available. By using European samples, it might make a SNP variation which is rare in Europeans look more important than it really is. But if it's common in other ethnicities, or in a combined group, it suddenly looks extremely unlikely that it could be causing problems in their customers, since billions of other people have the same variants.