I have noticed of late that the dna tag is not being used very often when applicable, or is even being removed from many DNA questions. It sometimes seems to be replaced with autosomal-dna, y-dna, etc. rather than just adding that additional tag.
I think that all DNA questions should be tagged with dna as well as any subcategory of DNA, if relevant. If someone wants to "watch" DNA questions then it makes more sense for then to have to watch one tag rather than going through all the subcategories of DNA.
It is not redundant to have, for example, both dna and autosomal-dna on a question (and these types of questions rarely run into the 5 tag limit). Using both tags is consistent with what is done on other sites, such as StackOverflow, where it is encouraged to use both the more general tag (e.g. excel) and the version (excel-2010).
Our other option should be to remove dna altogether, and categorize all DNA questions into autosomal, x, y, or mitochondrial, but I think that would be a mistake.
Not saying this approach is necessarily right, and open to other ideas. Just going for consistency.