I really don't see what's so "silly" about discussing the compatibility of different races. Topics such as whether the 5 races are in fact similar races, or entirely different species (And if the latter, that also opens up questions about how else they can differ. Medicine would likely be a nightmare), or inter-racial tensions (Sure, the races might play nice on the surface, but you're likely to get disowned by your family if you date that miqo'te that caught your eye) can be interesting and informative.

Not everyone giggles like schoolchildren when the topic of sex is brought up :P