I have one male patternless and i have noticed that his color darkens when it is cold. also it really brightened up after he got over being sick. So in my experience, they change a little bit depending on its surroundings.
Also for the parents to baby thing, Ron Tremper had a page on his site that can explain this a little better than i can but I can try. Incubation effects the outcome of the baby with sex and color. The higher the temp of incubation they brighter the leo. So even if a leo is dark, if it was incubated at a lower temp it could not be showing what it has potential to show. What I mean is that a baby can have the genes to be very yelow, but it can still come out dark if its incubated low. But it can still produce very yellow young because it has the genes.
so if you want females that are really yellow, you can incubate them low for the 1st two weeks, then increase the temp for the rest of the time. but don't let the temp drop to long after that. in just a few hours at a low temp, your baby can darken. its a science thing.
check out www.leopardgeckos.com for more help. because I don't think I understand what I was trying to say myself. I hope I can help you a little though. good luck, and i want to see pics.