Defoliation question

Genetic variance is always possible, but most plants want a similar diet. Definitely behind the different pattern of growth (lanky vs bushy). Need clones to consistently avoid that deviation. Hard to tell if it is growing faster since there is a week difference in growth. It may need a high concentration of nutes if it's a stronger plant to support the extra growth rate. if they are in fact similar and the difference in size is 100% caused by difference in age, it could be a sign the soil you use is losing it's charge and you need to fertilize more... seeing the future, so to speak.... if you use soil.

Could be the same plant cultivar but things very greatly from plant to plant. Think of it like two parents have two kids, both girls. Well they are sisters yes, but both are different. Same way our plants work. As far as the yellowing, it looks like you need to up the fertilizer on that plant a little. In doing so, after about a week it will regain its color. Hope this helps.