Here are my own personal examples:
I have 11 BD's of all different sizes and ages. Of course all of our males are separated. But I took in 2 3 year old males that were housed together. One obviously became the dominant one and beat the other one up badly. He is very aggressive, even now by himself, but in this instance, he was given the opportunity to become a dominant male. So I can see how this kinda changes my theory but the submissive one is a little puppy dog. While all of the other males turn black and do their ritual dances, he just ignores them AND the females.
I have 2 females that I acquired at a few months old. They are both together in an 80 gallon tank. When they got a little bigger, one must have nipped the others tail and it broke off so we divided the tank. Before we separated them, they were very loving and super friendly. Since we separated them, one of them turned into hell on wheels. She goes to bite you when you try to pick her up. She opens her mouth and hisses. The other one is perfectly fine. They are a year and a half now.
I have 2 other females in a 40 gallon tank, one is a little larger than the other. They are like 2 peas in a pod. The smaller one is usually found on the back of the larger one and both are very pleasant to interact with. The larger female in this case is our current breeder and after just one mating, she has produced 3 clutches. I jokingly said to my brother that we must be doing something right for her to voluntarily become pregant again on her own.
Now while the above examples niether confirm nor deny my theory. Observing the changes made me think about it a little more but I needed to find the right people to pose the question to.
Here is my best and most recent example.
I have 11 3 month old Savannah monitors and 1 5 month old (he is not much bigger) The 5 month old I purchased before the babies came along and I kept him in a small tank on my computer desk where I work from so that he would see me constantly and realize that I am not a threat. I know they are not the most pleasant but he was a little hard to deal with, but I understood.
So then the babies came along and I keep them in a super large tote all together. None of them are aggressive, at all. Now feeding time is quite the opposite, but I understand that. But to try to shed some light on my theory, I took 2 of the larger babies and put them in with the 5 month old and low and behold, he calmed down tremendously (after a few hours of huffing and tailwhipping the new guys) and now I can take him out and enjoy him as well as the others.
I might not have a ton of examples and like I said, some of these things happened under opposite circumstances but after you do all the factoring (species, age, size, sex, etc.) is there any kind of backing to this? It was just one of those things that make you go hmmmmm....