So I had my DNA analysed by 23andme and the most significant results are not a huge surprise.
I have the common mutation on the MTHFR gene, the methylation thing. Would that mean that I can't trust the results of my folate tests? If I've understood correctly the mutation may mean that the folate pools and doesn't break down properly.
Also got a crap load of mutations associated with coeliac disease, type 1 diabetes, lupus and vitiligo. Pretty much the autoimmune motherload... Of course, merely having the mutations does not mean that these diseases will ever rear their heads but it's nice to be forewarned!
Also vindicates my decision to adopt a gluten-free diet, given the skin and intestinal relief it's brought.