We are shedding skin all the time. Most of the housedust that
accumulates is old skin. Aliens (if they exist at all) would have no
difficulty is obtaining abundant DNA, not only human but of dogs cats
etc. I thought this group was supposed to be about DEBUNKING
pseudoscience, not putting it forward.

Incidentally flying saucers are terrestrial. In

http://myweb.tiscali.co.uk/ianandmargaret/FlyingSaucer.htm

II have solved all the mysteries of flying saucers, except one. They
are in fact serious aviation and work with turbofans. Not antigravity.