Plant traits in hybrids

I've been noticing a sort of unusual pattern in my bagseed grows. Many of the plants start out with indica like traits, some have even attempted to go straight to flower after the coty's dropped off. However, out of the last 10 plants grown from seed only one has shown indica dominant traits to the end. I know most of the bags I smoke are indica based, though the seeds usually come from a variety of different bags.

Is there a way to discern just how much of each type is in the plant based on growth rate, bud formation or genetic strengths and weaknesses (ie: natural resistance to pests)? I have this horrible habit of harvesting my plants a week or so early because they don't all finish at once witht the differences in genetics, though I'm hoping to resolve this with clones.

Also, can this sativa-like appearance be caused by using florescents in flower? I will have my HPS in very soon but haven't been using one previously.