It's not as if this type of

It's not as if this type of smile would be used for police to go door to door looking for people that smile a certain way. It would just allow scientists to isolate the faulty gene if there is one.

How do you know that it wouldn't be used this way by the police? I can easily envisage policemen knocking on doors with a computerised gadget designed to scan and identify people with 'pedosmiles' by using facial recognition techniques, if there is a dangerous pedophile on the loose, just as they have also mistakenly used lie detectors for years in an attempt to identify liars.

The pedosmile isn't supposed to be an indicator of pedophilia. It's a possible link to a larger issue. Essentially if there is a link between the two, it could point to what gene causes it (if there is one). In other words it could lead to a cure or a genetic "patch" so to speak. 

There's also quite a bit of evidence that many pedophiles claim to have been sexually assaulted themselves as children, though I suppose there could still be a genetic link if the pedophiles that assaulted them were genetically related.