I'm a really anxious person, so I tend not to keep secrets. I tend not to even want to hear them. It's too nerve-wracking for me to try and keep things from people.
The more people you run into, the greater your exposure, the easier it is to understand and empathize with other people. So if you are living in a much smaller ecosystem, it's probably easier to have simpler feelings.
As your life goes on you should gain a deeper understanding of the world and the people moving through it; but that might be asking too much.
No matter how old you are, if you're just not an empathetic person, it's a lot easier to concentrate solely on something that is injuring another person to even some score. Hopefully as people grow older, their ability to empathize deepens.
Secrets are always never as well kept as people think they are. More often than not when you reveal something, especially the bigger it is, people always had some inkling, or they're like, "Well, yeah, of course."