Does this plant just have bad genetics?

I cannot figure why just this one particular plant is very droopy. It's my biggest plant and seems fairly healthy except for sagging. I must say that it has always seemed weaker and limper from the beginning despite being the faster growing plant(btw, the smaller was started two days later than the others but is still slower growing anyway). Ph is fine and I have a nice bubbler in the res providing oxygen. I an using Dyna Grow Gro nutes. Neither of the other plants exhibits the type of droop of the biggest. I believe I have a skight calcium deficiency judging by the rust colored/brownish yellow spots on a few of the fan leaves of the plants, but that is about it. Wind flow is fine too.What could be the issue with this plant? Could it just be poorer genetics?

Also, I do notice the newer leaves twisting a bit as they start out growing as well as the look of something eating at one spot on a couple of the leaves of the dropping plant, but it's just on one set of fan leaves and only in one spot(I tried to show this in a pic but not sure how clear it is). I know that nothing is actually eating it though. One more thing... do I start counting nodes with the bottom set of leaves with only three leaves or at the first set of five-leaf fan leaves?

i honestly dont know man....you awnsered the first question that i thought of wich was a slight nutrient diffenciey ....actually i think that ,..that may be youre best shot beacause obviously theres some type of dif going on there you can see it on the leaves of the plant thats drooping.i think the best thing would be to pin point what that slight def is and get it fixed and that may be the key to your problem...good luck

It not yo genetics looks more like over watering
too much or too long at a time. What the ph/ppm?
It does looks a little hungary~

I think me and you have identical twins. peep my journal. Is that Dead Head OG by chance?