What colour is this dress?
White and gold
Blue and black
Click through to this Wikipedia link to discover your phenotype:
Perception of colour is a complex cognitive phenomenon. Nevertheless, there are some underlying genetic determinants of colour-perception, for example colour blindness.
The dress pictured caused a viral sensation when variation in its perceived colour was discovered.
If perception of white/gold versus blue/black in this picture is under control of a single locus, we may have a chance to narrow down its location via OpenSNP.
Alternatively, variation of perception of The Dress may have nothing to do with genetics, which is also an interesting answer.