A Unicorn is a horse with a horn on it's head.
Evidence that Unicorns exists:
Horses are real. Although i'm not personally familiar with horse DNA profiling, i'm pretty sure that there is a wide variety of DNA sequences recognised as being horse, or another equestrian sub-species such as zebras and the like.
Horns are real. There's probably DNA markers for them too.
There are animals with horns on their head, like Rhinos for instance. Therefor there must be a DNA marker for that.
Therefor from a DNA perspective Unicorns must be possible.
Is something real because it is possible?
According to n-dimensional physics all possibilities exist simultaneously at all times - or is it that all possibilities don't exist at all at all times, except the moment that is - ie: the universe existing for a brief fraction of a micron of existence in the reality that we think we are experiencing in a temporaly linear fashion on account of our recollections of the past and inability to know the future (but what is memory other than a perception?).
Anyway my point being, the most advance sciences known to man may not have uncovered the mysteries of the universe, where we came from or how the universe was made.
But they clearly provence the existence of unicorns*.
*Albeit perhaps at a different position on the 4th dimensional axis.