Reptilians use technology to shape shift.

They developed technology to artificially enhance their own DNA.

The shape-shifting technology comes from the reptilian's advanced understanding of Quantum physics and our holographic reality.

They can manipulate how we see things as they understand we process our visuals through code within the photons of light in our immediate surroundings.

They also know we only have access to 0.005% of light within our visual spectrum so it is really easy to fool us.

They essentially can hack into that holographic code and change it.

This is similar to how virtual reality would operate and distorte our natural perceptions. Therefore they can project an image of themselves to us through a so called 'skin' which is a fake holographic identity which we perceive as real.