everybody will always have some muscle group that responds better to some workout strategies than others - until you have tried ABSOLUTELY everything, anything chalked up to bad genetics is a cop out IMO
looking at your leg workout already screams OVERTRAINING
I used to have shitty delts for a long time; I started going low reps- super heavy and boom; they grew - they're the best bodypart now
I thought my legz were cr@p; I took my friends advice; went lighter and super deep on everything and split the ham/quad days .... boom, my legs have grown nicely so far
dont mean to come off as an ass bro; but until you give every method of training a go (like so many these boyz have suggested) and see how your body responds, you shouldnt pull the genetics cards - not for us but for yourself...dont give up so easily on yourself
cheers