BTW: in my opinion, Krans do NOT have feelings like love (remember, it's chemistry) so please DO NOT flirt 
If a Kran was raised by a family of another race, arguably it would learn to imitate aspects of that race such as emotions. I suppose it's that whole agrument of 'can a simulation ever be the real thing' but I believe as far as all outward signs are concerned a Kran could enjoy flirting
Another point to make, if a Kran could not feel love, it continues from there that it could also not feel compassion, empathy, it could have no like or dislike or preference, it would not feel any need to converse, interact, or do anything other then what is strictly necessary to continue it's own existence.
Well how do rocks reproduce then 
They're not rocks so much as they are a kind of firm rubbery thing, i think I read somewhere. At least that's what jumps to mind when I hear 'silicon-based life form."
If they were made of actual rock, they would be near impossible to kill or injure. Also they probably wouldn't be able to move.
In MY opinion, we have to assume that Kran are bio-organisms the same as anything else, they have chemical bodily fluids and systems and etc, it's just a DIFFERENT chemical from the rest of the races.