Are mermaids fake?

Afraid so.

Only if you want them to be :)

Well, there is a 'sea ape' theory which suggests that many years ago some humans (in the early stages of evolution - probably Neanderthals or something) lived in the sea and developed characteristics to be better suited to the water. The theory splits a little bit here.

1- Some people think that this explains why we have slight webbing between out fingers and why we have virtually no hair whereas most mammals are covered in fur. However this suggests that modern humans evolved from these sea-apes, whereas the original theory says that the early human population split - some lived on land, some in water.

2- The sea-apes' 'legs' eventually fused together (some people claim to have found these forms - there are pictures on the internet so you can have a look for yourself) which could be where the modern idea of mermaids comes from.

Personally, I like to think that mermaids - or sea apes - were, at one point, real, but if they were it's likely that they died out a long time ago. Having said that, however, we've explored less than 5% of the oceans, so who knows what could be there? There's also the idea that the prehistoric megalodon could be still swimming around somewhere.