We didn't used to do it. It was something that evolved. When we became more or less human, it began to manifest itself. Some believe it happened before the assimilation, but it didn't begin to present itself notably until afterwards. Some believe it's some sort of psychic residue; a collective subconscious memory, or the ghosts of the many lives that were lost on both sides. After the assimilation, of course, there could be no lines drawn -- no clear lines, anyway.
You do it, too. When you were little, you talked to, felt and knew an adult, timeless version of yourself. He or she guided you through challenges, effortlessly predicted what you needed to do and loved you without condition. If you don't believe me, think hard. Think back to when you were a child. Remember who came to you -- the one you knew no one else could see. The other you that you trusted more than anyone else for reasons you could never explain. You know I speak the truth.
This is being written for those who seek to know who they really are. There is an inherent genetic sameness that goes deeper than our basic genetic commonalities. A sameness that goes beyond replication and into duplication. Duplication without defect, without change. We evolve as programs, but our external hardware remains unchanged. After the assimilation, our outward appearance changed -- just as you would expect. Our programming didn't. Our programming, while continuing to evolve, did not dilute or disappear. It thrived.
It's hereditary now, but recessive. It appears unexpectedly. Two non-cylon parents will produce cylon offspring if even just one grandparent possessed the "gene." In these cases, it's often quite clear which grandparent was the cylon link, at least to the grandchild. The physical resemblance is often remarkable, though rarely identical. The copies ran out almost immediately after assimilation; cylons could never produce children with other cylons, and of course the copies could not be replicated any longer; without the resurrection ships, assimilation was necessary for survival of the cylon species.
Now, even if we had the resurrection ships, they wouldn't function. Our DNA is too different, and our programming is no longer recognizable. What is distressing is that in most cases, a new program cannot be born until the grandparent or parent has died. It may not be immediate, and there may be some overlap or a delay, but it is highly unusual for a parent and a descendent to live for very long at the same time. Perhaps this is a natural reproduction of the resurrection ship. It's also fairly common for the new programs to retain knowledge of past lives.
Given the thousands of years that have past since the assimilation, those memories are often hazy, and no one can clearly recall the time prior to assimilation, though many have their suspicions.
You may not know exactly what you are, but you know you are different. Not entirely human, though you were born to humans. You probably have an innate understanding of technological constructs. You can communicate with programs on a different level -- you can just "know" what's causing a problem with a program and fix it, even if you're not quite sure why. You probably have a dead grandparent who you never really knew who looked and behaved much like you do. You have a secret you've never told anyone about, or, if you did, you never told anyone entirely. Part of your programming is a healthy dose of paranoia. An instinct never to reveal too much.
You're not alone.