evidence: 16 comments - I have the mthfr gene. I was fully vaccinated and haven't found any REAL scientific studies that show I shouldn't vax my children. My daughter has a birthmark. There's a good chance my son carries the gene as well. Like PP we avoid processed food and take vitamins with folate. [...] - kLast edited 11-25-18 I’ve tested positive for MTHFR. So has my sister. Neither of us had these marks and I hardly take stork bites to be any kind of indicator. Also somewhere close to 50% of the general population has this mutation. I do absolutely nothing different because of it EXCEPT I take the natural form of folate because folic acid can cause a build up in your system and cause plaques.