It looks like bad genetics or a poor transfer of genetics, u could re-pot it to make sure its not rootbouand for that size it looks like it wouldnt be but the roots may have grow very big.

If it has anything to do with genetics all the clones will act the same, with some varying but it will be on avegerage with what this one shows. The bigger one looks small too?
JackdaWack Reviewed by JackdaWack on . The DWARF phenotype----? AAAAAIIIGHT! lol so, I plant two seeds on the same day, the same size, same strain(bubblegum), grown under the same light. One is already in flowering, and doing pretty good for its size. The second, seems to be a Dwarf-? its the same age, but its only two inches tall at the most.. at first i thought it was just growing slow, then i realized it was just as mature as the rest, but tiny (the first two leaves were literally miniscule) anyway.. i decided to keep the little blighter in veg, and Rating: 5