Remember those census forms that we will fill out every so often, where we live how many people in the family etc. Wouldn't it be cool if there was a census to discover people to mermaids or mermaids to people, all you would do is checkmark one box if you are 100% human or 50% human 50% fish, then we could find out if mermaids/mermen 1 in every 200 people etc and do this for the whole population.
Would be curious to know how many mer people are in my area :)