One of the more important empirical aspects of this theory is that it is possible to match all of the colors in the visible spectrum by appropriate mixing of three primary colors. Which primary colors are used is not critically important as long as mixing two of them does not produce the third.
Modern color scientists have put great effort into determining that there are indeed three classes of cones, that their outer segments contain spectrally selective photopigments and in determining the spectral absorbance of these photopigments.
During the last 15 or so years geneticists have and continue to investigate the genetic basis underlying trichromatic vision. They have indeed been able to identify the genes that are responsible for the receptor photopigments.
It was popular in the first half of the 20th century for authors to pit the trichromatic theory against the opponent processes theory. But in fact both theories help to explain how our color vision system works. The trichromatic theory operates at the receptor level and the opponent processes theory applies to the subsequent neural level of color vision processing.