"could be a number of things.. were all the seeds from the same bag? could just have different traits then the others but either way .. it is impossible to determine between sexes this early. looking good though.."

absolutely. leaves look different from strain to strain. some never have more than 7 leaflets, some have several leaves of 11. big differences develop at the beginning of flowering. some strains show their sex quicker than others; some accelerate vegetative growth at the beginning of flowering more than others