I see what you are saying. My problem with all of this is that I have been told to ignore MTHFR, Plus, heterozygous anything, the 7++ corticoid receptor genes, the corticotropin releasing hormone genes, the TCN2, MTRR and so on.
These are very different issues than suggesting that the common methylation SNPs that most people have are also making them (most people!) extra prone to problems with metals, or anything else in general. The common MTHFR mutations do have an impact, but it doesn't cause wide-spread problems because eating a normal amount of vegetables full compensates for it.
Heterozygous SNPs can have an impact, but they are also usually extremely common, especially the ones listed by Yasko and similar sources. SNPs on those genes certainly can have an impact, and even cause disease - but we can't just play "count how many are homozygous" or even pay much attention to ones which have a shown a tiny impact that is likely the result of poor statistical methodology. The reality is that everyone has thousands of such mutations, and most are having absolutely no health problems.
Due to the poor quality of information regarding SNPs from many commercial sources, patients are put in the position where they have to become something of an expert themselves, or they end up relying on upon quackery.
I had my colon removed because of epigenetics. Can modify gene expression increase the likelihood that a person's m-pathway SNP's might become an issue?
No. Epigenetics is basically what happens to a gene, or the enzyme it produces, from outside of the gene. So a factor which is external to the gene steps in and (typically) up-regulates or down-regulates it. This can result in more or less of the enzyme. But it does not somehow cause a SNP inside the gene to behave differently, or to become more or less "expressed".
The word "epigenetics" itself is a good indication of what is happening. "Epi-" is a prefix meaning "near". Hence it's factors which are "near" the genetics of an enzyme, but not actually an integral part of the genetics. SNPs are an integral part of the gene - they can cause an enzyme to be formed with different amino acids, and/or a different structure, and even have a direct impact on how much of the enzyme is produced, depending where the SNPs are on the gene. But epigenetic factors are only capable of influencing the entire product of the gene. They can't reach inside the gene and change how a SNP is functioning.
But some people, when called out on Yasko's claims being completely disproven by scientific research, will resort to hand-waving and some vague mumbling about epigenetics and gene expression potentially causing a SNP to suddenly do something radically different. They simply have no bloody clue what they are talking about.
If you are really interested and your brain is up to it (mine certainly wouldn't be currently), Coursera has some very good introductory genetics classes. They're free, and there's no harm in learning what you can and not worrying about the rest if crashed, etc.
A couple intro courses that sound decent:
https://www.coursera.org/learn/genetics-evolution - 11 weeks, unknown hours per week but sounds easy
https://www.coursera.org/learn/genomics-research - 6 weeks, 6-8 hours per week
And also maybe interesting, after getting a basic background:
https://www.coursera.org/learn/genomic-precision-medicine - 7 weeks, 2 hours per week
https://www.coursera.org/learn/epigenetics - 7 weeks, 6-8 hours per week
Full list of genetics courses at
https://www.coursera.org/courses?languages=en&query=genetics