A virus makes you
fat?
A virus makes you
autistic?
A germ makes you
gay?
A germ makes you
schizophrenic? (Remind me not to go near cats).
Maybe, maybe not, but viruses/germs are ubiquitous and genes are not the be all and end all.
Also I would like to take this opportunity to coin the word "germes" for foreign DNA/parasites that have effects that seem indistinguishable from genetic. For good measure, I also coin "germome", and "germetics", and "germealogy" (yes, that's how you spell it).
Start using these words immediately.