yep possible, ive cracked different strains, same environment same everything, some flew off, some were slow growing..
As for 'bad genetics', wots bad?, its just a trait
i seen too many different reasons for slow growth to be certain that there really is any one cause. right now ive got 5 trainwreck(all same genetics and grown from seed in exact same environment)and each one is different, but i just kinda know that its all gonna level out at some point. my last grow(thechurch and la woman) was the same, at the finish most came up with the same amount but differences in the look of the growth was huge. if pushed i'd have to say that environment is the main reason but really the philosophy 'shit just happens' would probably be the most accurate assesment.
i use seedling/cutting soil with a bit of perlite. i wouldnt even dream of adding nutes at that stage. after a few weeks i use miracle gro soil(which a lotta people fuckin hate becoz it has slow release nutes) ive never had nute burn.ever. and my yeild is fair/decent. i dont go mental over nutes, i use bio bizz grow and bloom and for the last few weeks mollasses. watch out for nute company claims that'll tell u that u can grow a fuckin giant redwood in 6 weeks or whatever. the nutrient business is full of fuckin snake oil salesmen.