Well, it’s kinda how our brains work.

I’m not sure how much I can go into without needing to point to psychology, which is pointing to authority, so take it as you will.

Look at what happens when a traumatic event occurs. The brain takes it, and lays down a big “warning” patch, so that when similar things occur, it can react before things get as far.

Then, look at the way we’re social creatures. There’s chemicals our brains and bodies dump when we do good things with people.

Then, look at child/parent bonding. Those chemicals mentioned above trigger heavily when a child is in contact with a parent (biological or otherwise) in early development. This means that before genuine sapient thought can occur, we are linked to our parents by our brains and chemicals. There are things that can prevent that bonding from child to parent, but it’s actually pretty difficult, far more difficult in things that prevent parent to child bonding.

Next, the onset of abuse is rarely during the earliest development. And I say that while holding neglect and/or emotional withdrawal as a different thing, which is the more common way an abuser is going to start, but is a form of abuse. It just isn’t traumatic in the same way.

So, we’re at the point where abuse begins.

The initial trauma is weighted by the brain just like any trauma. But it’s weighted against all the pathways and memories engrained before that. It weighs the abuse against the dependency of child on parent. That means that in order to later disconnect the effects of the abuse from the victim, they have to also strip out those connections.

The more abuse, the harder it is to untangle things.

While the abuse is ongoing, a child has little or no ability to compare it to anything. The abuse is their baseline for what life is like.

Even when working on that via therapy later, you have to rebuild a new baseline to build healthy patterns on.

Then, that abused person has a kid.

Unless they’ve gotten very, very far into healing and rebuilding, every single interaction with their child is being held up to, compared to, whatever memories and experiences they have stored. They’re using whatever coping mechanisms they learned. Those things are all dysfunctional.

So, even though they don’t necessarily want to abuse, their first responses are going to come from a brain that’s been shaped chemically and physically by abuse. Their kid does something “bad”, based on those flawed patterns. They have whatever pattern they learned to draw from to decide what to do. Sometimes, they may not have developed enough control to have a choice, they may react before they can choose.

Since what they know about parenting is wrong, unhealthy, the less they’ve learned that counters the abuse, the more likely they are to use the tools they were taught to use: abuse.

Since that abuse fills them with fear, anger, and possibly a deep resentment of those that didn’t experience abuse, they’re now at a disadvantage regarding their ability to bond with their child. A weaker bond makes it harder to stop and think instead of just reacting.

It takes active, long term work to rebuild the brain and the mind within it. It’s a process that can take longer than a lifetime. Often enough, the life choices made while trying to move forward after abuse make the abused more prone to self medication, to risky behaviors, so you end up with them making kids well before they’re ready, which maximizes the risk of them abusing.

When they do abuse (and it is not a guarantee), they’re imprinting their kids with the same patterns.

Now, even in those that escape the cycle, that do the work, some are still going to have dysfunctional practices. They may not have reached a point where they can implement best practices at all, so it can take multiple generations to filter out.

An example of that: parent A beats their kids with rolling pins and sticks. One of those kids rejects that, but is still working with the need to parent, and only beats with a belt. Their kid only beats with a hand. Their kid stops beating at all, but still spanks. Their kid rejects spanking, but still yells, possibly also engaging in non physical abuse as well. Their kid finally rejects that last layer and raises their kids not only without abuse, but while trying to apply best practices. It’s that next generation raised with best practices that finally raises kids that are no longer part of the cycle.

At any point in that, the next generation could regress, even at the very end where they were raised as well possible, without anything remotely abuse. They could, for whatever reason, become abusive instead of continuing a cycle of optimized raising.

It’s important to restate that physical abuse isn’t the only form of abuse. I chose it as the example because it’s the most obvious and easiest to use as an example since there’s no mistaking a beating for anything but what it is.

It’s all about how traumas shape and change the actual structure of the brain in an attempt to avoid future negative events. Once shifted enough from what would be ideal, the road back towards a healthy state of being is both harder, and less certain of completion. There’s some people that will say you never totally remap yourself, you just build enough layers on top that it prevents the old pathways from activating until and unless a new or repeated trauma rips all of that up.

You don’t necessarily have to cut anyone slack. It’s a good idea to try to, because you never can tell when a bit of empathy can be the thing that lets them take the first step out