Why can humans not inherit memories? originally appeared on Quora, the place to gain and share knowledge, empowering people to learn from others and better understand the world. You can follow Quora on Twitter, Facebook, and Google Plus.

Why can humans not inherit memories? The short answer is that memory is the result of experience, something that is not transmittable via genetic material. Let me paint a picture, hopefully that will make it easier to understand.

This is a house, a standard house. It’s empty but has all the things needed to be a house. It has four walls, several rooms. There’s a living room, some bedrooms, a kitchen, some bathrooms. With the blueprint below you can build as many of these houses that you want (or well, as far as your resources allow).

There are many identical houses, but each one is unique due to the people living there. Now to loop back to memory and genetics.

What our parents give us is the blueprint, the instructions to build a human (or more specifically to build us, since it’s a mix of two blueprints). It’s not a total blank slate, no. Much like a house isn’t just four walls, it comes with utilities, bathrooms, a kitchen. Humans too have some extras included, walking, talking, senses, intelligence, and personality, so much stuff comes packaged in our genes. Over time, a house becomes a home, and over time, a human becomes a person (and that starts before you are even born). Memories and experiences make us who we are. The way we live influences how our genetic potential comes to fruition.

The brain, when just formed, is a total mess though (like on the picture below on the right). It’s a huge web with more neurons and connections than we even need. This is on purpose. Neurons are special and we only grow them when we are young. Because we can’t grow new ones (in sufficient quantities that is), we overshoot and then prune back to the most efficient form. Just like how you grow a bush and then cut it into shape rather than try and grow it into that neat bear form.

We don’t know exactly how memory works just yet, brains are really complicated so we need some more time. But we do know some stuff. The best way to think about memories is as a web (and not like a computer file!) A memory is like a path, carved through the web by connecting various neurons. In the image below, that would be the green and the red path, two different memories. In reality, this is of course is a lot more complicated, but you get the idea.

You might already see the difficulty in inheriting memories. To inherit that memory we need to have specific instructions to make a very complicated pathway, connecting many concepts together. Oh, but then we also need to pass along the instructions to form those concepts, which require other concepts… and so on.

That’s problem one, each memory is different and if you and I have the same memory (say some math concepts, or 9/11, or the moon landing), that same memory has very different paths in different brains.

The second problem is that, even with these instructions, there’s no mechanism in place to actually make these connections. I said before that we are born with some utilities. Humans automatically learn to walk and talk, but that requires a lot of practice. Our biology is very much predisposed to make that possible, but those pathways need to be made. Only a few things don’t require such learning, like reflexes (but let’s not get into whether a reflex counts as a memory).

We are simply too complicated to pass on our memories, and the way we grow simply doesn’t allow that. We have to do it the old-fashioned way by means of teaching and sharing our experiences.

Having said all that, not all experiences are lost. Epigenetics is showing us that to some extent the environment can alter how genes are expressed, this change can be passed on to offspring. If something happens that forces an organism to adapt, like a famine, these experiences are passed on. The offspring has now inherited its parents experience in some way.

To relate it to the example, experiences can cause some changes in the blueprint. This change is then passed on. Other houses are now being built with an extra wall or solar panels. But each house eventually becomes a unique home, and each human becomes a unique person.

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