You said those are a few weeks old in that picture? Hmm, mighty small to be that long into veg IMHO. They aren't getting what they'll need to produce any quality on that window sill.

I'm just guessing here, but it sort of looks like they are stunted on growth being thrown in and out of a vegetative state repeatedly. (no plant likes to be deprived of light and then overwhelmed by it, then deprived and so on it stresses them out completely) If you are lighting for the veg state keep it that way for a minimum of 3 weeks. (On these plants pictured, you may have to go a bit longer to re-convince them they are vegetating) If you are lighting for flowering stage keep it that way until harvest or re-vegging.

Others may have different ideas on your grow. Best of luck to you!