Why are they flowering?

And when I returned half of them were flowering and the other half were not. here's a summary of the story:
Now at about six different genetic strands.
These six different genetic strains were placed in very small flowerpots when they were rooted clones.
Under a light cycle of 18 hours on six off and they started to takeoff growing then it was decided that it was better to move plants outside.
-so a declining light schedule to match summer solstice June 21 was to be the move out day.
-That current schedule was a reduction in light of approximately 30 min. a week, until it matched up with the Summer solstice, now with weeks before synchronization.
-Half of the plants are now flowering and the other half are not.
-This brings me to question are the plans flowering due to root stress from being in a tiny pot?
and/or
-some genetics have a different light cycle,right?
-So I have found some plants that will flower at about 14 hours of light and the other plants need to continue to drop the light cycle, to find out what point the other plans will Flower?

The small pots are making them show sex. It should stop once repotted

It's because you reduced the photoperiod and the long nights caused starches to build giving the plant an internal message 'start bloom now'..

Usually in this situation,once the plant realises the day length is still lengthening outdoors,it will kick back into veg shortly. This tends to have the effect of shortening the internodal spaces and results in a much bushier plant than normal,sometimes so dense that flowering will be retarded unless the sucker branches are pruned out in a timely manner. I know some outdoor growers who actively encourage this to happen as they believe they get a better quality bush at harvest from having done so.

It's also true for some cultivars (more than others) to have a stress reaction to being rootbound that causes them to flower prematurely in those conditions,and for those plants,a more roomy pot/bed would likely reverse the premature blooming.

Ok, we all agree that a 4 foot plant should not be in a Dixie cup, and could play a factor.
But then in that case would all six plants be flowering.

-In nature the daylight cycle changes a 1 min. or so a day... With the reduction of 30 min. a week. (with my lights)This may have stimulated the flowering response.

-Left was question do I transplant now and continue with light cycle synchronization with summer solstice. Or just wait for transplant then?

-June 21, 2017 there will be 14:41 hrs of daylight
-daylight will get shorter every day until winter.

I believe the photoperiod variability will be the most likely cause of your early bloom,with rootbound as a possibility.With regards your query about why other plants of the same strain are not also showing pistillate growth,I'd put that down simply to phenotypic differences between siblings.
My advice would be to pot them on or transplant to beds asap,and look out for the typical 'reveg' signs, e.g. reduction of leaf blades down to either sets of 3 or even 1.You may notice top leaves lose their lustre and maybe even some or all of the serrations,and top growth will be generally 'ugly' looking. Don't be concerned about it,it's all a sign that you called it and did the right thing by potting on. Like I said this will cause you to end up with a denser and more squat plant at end of life,which has the potential to choke itself so prune accordingly. I have seen plants which you could not see any light through whatsoever before being in full flower when they've been tricked into starting bloom,then began vegging again,and shortly thereafter back into bloom.
Good luck with your grow

I would say that a high percentage of plants would show sex being 4' tall in a dixie cup. But it could be the photoperiod as well. Doesn't matter. Get those ladies into bigger pots or in the ground asap.

I'm assuming when OP says the plants are in bloom he means they're actually expressing pistillate growth at the tips rather than leaves..

I guess the poster above could be quite correct,are your plants showing preflowers or actually in bloom? I have definitely come across growers before with a year or three under their belt that did not know what pre-flowers were..often these guys would be indoor growers of feminised seed only,triggering bloom very early. I shared some clones with one such fella and he could not get his head around the idea that a mature plant will show preflowers even in veg.