Yeah no one can tell you this with certainty. Even the breeder itself would not be able to make that distinction if it came from seed - may be possible with clones but not from seed.. too much variation of the genetics to be sure.
Granted, once its flowering and getting close to harvest - it may be easier to give an opinion. For instance, You might get some lemon terps coming thru on the lemon OG kush. There is much more expression of genetics in flower, so youll likely have to wait until then to make a somewhat accurate guess. Sorry!