The Human Genome Project turned up some very interesting information about the methylenetetrahydrofolate reductase gene (MTHFR). It turns out that a significant portion of the population may suffer from a defective SNP that has potentially destructive consequences for our health. The good news is, prior to contrary beliefs, our genes are entirely mutable (i.e. we can change or affect them) with diet and nutrition! So despair not, and read this article that makes this difficult-to-understand topic a bit easier to digest.
You can find out if you are among those affected by MTHFR by taking a simple DNA test from www.23andme.com. And consider supplementing with a B complex that contains Metafolin or 5-MTHFR.