very nice
feeding and oxygen levels can have an effect on the stretch of your plants, but most of the time it is a genetic thing... or at least i would say 90 percent of it is genetic.
the other thing that can have an effect is the type of lighting used. for instance if you vegged under a MH or floros with the light close, you will get much closer internode spacings, so that when you flower it will not be as stretchy as vegging and flowering under hps.
did your friend use the same mother as you or does he have his own? like i was saying he may have a more indica pheno, whereas yours seems to be more sativa.
i had one run with some chronic that my buddy was getting rid of, and i ran 16 of em in hydro, they were EXTREMELY indica phenos. i flowered em at about a foot and a half and they only got about 2 and a half feet tall and was just a solid bud from the bottom to the top.. to this day best yield i ever had doing hydo which was about 2.25 lbs off of a 1k light. i wish i had kept it around but i didnt know how great it was and i had just got started in growing and wanted to experament around.. i am however about to order some more seeds from attitude and bring her back to life!! great smoke, great yields, what more could you ask for!