Whats up with my MARLEY COLLIE?

Whats up with my MARLEY COLLIE?
1000W HORTILUX/ co2/promix bx/fish/molassas/epson salt/tiger bloom/. I have two sister plants at 25 days of 12/12 and the one is doing this yellowing thing that i only ever seen it one other time and that was with this same strain same seeds .
The plants are side by side and the one is normal not a spot of yellow anyware . There both doing well they are identical. one no yellow at all.
Shes got alittle leaf curl alittle bit to much ferts but theres no burn anyware. Could it be a genetic thing?
Can't wait to see what this weed is going to be like i been smoking indica weed for the last 6 years now i want a good day time weed so i had these seeds and i'm sure i can make do well .
They are growing well. Thanks .
peace.

Definitely a non-mobile nutrient deficiency. My best guess would be either Iron or Zinc. If you are using straight RO water that could be the culprit as it is lacking micro nutes.

The deficiency could also be caused by your pH being to high or low. Test your runoff pH to get a better idea. Do you pH your nutes? What is your medium?

i'd flush with ph'd water wait a few days then start feeding again lightly looks like an iron def to me could be caused by ph nute lockout.