I don't claim to be knowledgeable in this department ... but, I find it hard to believe that genetics rule in this case, at least not universally, anyway. I mean, consider how long it takes a Crappie to mature way down South vs way up North. Did the Crappie get "big" because of genetics, or because of a longer warm water growing season & abundant foodsource ?? (rhetorical question)
Did a big 'ol Southern sow Crappie get big simply because of genetics ?? I think not, simply because of the fact that a female Crappie deposits eggs in many different nests ... not just one. They don't all choose the biggest/baddest male on the block to be their babydaddy ... they spread their clutch out amongst several "suitable" males. ("suitable" being relative to whatever males are in the immediate area)
If genetics were the major ruling factor, you would think by now that some lake, somewhere, would be turning out 5lb Crappie as a matter of "normalcy" ... and that just ain't happening.
IMHO ... given all the variables ... and even giving the biologists credence ... if genetics played a significant role, most every lake would have a slot limit. They don't ... so one has to take into account what "limit" IS placed on ones catch, and abide by it.
... cp