Hi Lisa,
A reading of the IOM-dna webpages does rather suggest your interpretation - we have signs and fines and special dog litter bins in most areas where K9s take their people for walks - most Manx dog owners are responsible, but there are a few unsocial people who choose to ignore the problems they are creating - in restricted areas it only takes one dog a couple of days to cause a serious problem - responsible dog-owners are just as disgusted by this as non-owners.
The dna suggestion is a result of exasperation - the alternative line taken by some local authorities has been to ban dogs completely.
On the genealogy dna projects - watching the discussions over the years, most family history researchers do not have access to formal research funds available to academic racial-origin researchers and seem to be waiting for the price of testing to drop significantly further - I do not imagine there will be many comprehensive family dna projects until the price drops below £10 - which may never happen!