They are not related. George is 1 year older. I got him in 2013 and Holly a year apart in 2014. They are both neutered. Holly (younger one) has always been more dominant. George is very friendly and bonds easily and Holly was really mean for a long time. He is a lot better now and I can pick him up with ease, but I’m still careful on how I do so. George I can just scoop up any old way, but Holly might crab and bite if you don’t do it right. They both eat each day and have snacks. Holly will try to take George’s food sometimes, so he’ll usually go off to a corner to avoid this. When they bite each other’s tails, the other glider will curl their tail up, almost looks like a knot, and it becomes stiff because they are protecting themselves. I’m not sure why they’re doing this, but I went on vacation right before Christmas and my friend watched them for 10 days and told me this was happening. I witnessed it myself last night.