One of the oddest things about psychology is one of the most common dynamics defining our relationships.

It’s the power of the familiar, the gravity that can prevent one person from leaving the orbit of another.

In the physics of families, familiarity is the centripetal force that always pulls us back to what we know. It prompts decisions that defy logic, raise eyebrows, and elicit tongue clucks and head shakes. Our drive to maintain the familiar fills psychologists’ offices, courtrooms and emergency rooms alike.

I suppose it makes a certain evolutionary sense. For an ape, the troop you know may seem safer than the troop you don’t. For most of us humans, the relationships we know often seem safer than the ones we don’t, even when that familiarity includes pain. Abuse. Violence.

In fact, the familiar is so compelling that even when we finally break out of its gravity, we often go on to re-create exactly that which we’ve escaped.

If you’ve never been in an unhealthy relationship, these ideas may seem like so much empty psychobabble. But I would challenge even you, the least emotionally scarred and healthiest among us, to consider the power of the familiar.

Chances are you’ve looked in the mirror sometime recently, only to find your same gender parent staring back.

Chances are you’ve been startled to find that you want from your intimate adult partner exactly what you never got from Mom or Dad.

Most times, that’s OK. But other times, our need to maintain the familiar can hurt.

Growing up and growing away. Our job as healthy parents is to prepare our children to go out and live healthy lives apart from us. This usually looks like an awkward back-and-forth, hold-me-close, let-me-go dance that spans at least two decades and probably much longer.

We send our kids off to preschool and high school and college. We bite our lips as we take off the training wheels, buy their first 10-speed or hand over the car keys.

In each instance along the way, healthy parents give their kids permission to move a bit further away from the familiar, to risk the unknown, and we reassure them that we’re always there like an emotional pit crew, always ready to refuel them and send them back out there to try again.

Unfortunately, some kids are never allowed to venture outside what’s safe and familiar, or – just as traumatically – their efforts to test the unfamiliar are met with criticism, rejection and rage.

The mom whose anxieties convince her 12-year-old that the world is unsafe.

The dad whose fears for his growing daughter prompt harsh over-reactions to her early interests in boys.

These children are at risk of becoming terrified of the unfamiliar. They may experience chance and growth as threatening and cling to the familiar even when it compromises healthy growth.

Domestic violence. Worse still is the fate of those children who live in the midst of violence or abuse, who are terrified of what each new day might bring but even more terrified of what change might mean. They live believing they’re better off with the devil they know than the devil they don’t, fooling themselves that this time will be the last time, that if I can survive once, more maybe Mom or Sister or Brother will be hurt less.

These children often survive the pain of their family of origin, only to find themselves living a similar pain over again in their intimate adult partnerships, scared all along to give up the familiar.

These are the tragic souls whose stories – and sometimes their obituaries – fill our newspapers.

But watch carefully: Like the ex-convict who commits a crime because he doesn’t know how to function outside prison, many domestic violence survivors go right back to the pain they’ve so recently escaped. Yes, it hurts, they say. But it’s familiar.

Letting go of the conflict. Precisely the same dynamic is true for some post-separation, post-divorce co-parents. You might think the dissolution of the adult relationship would be permission enough to let go of the past, to move beyond the anger and fear and betrayal and loss to make a new life.

This is, in fact, exactly what the majority of healthy separated parents do and, in so doing, they bravely show that facing the unfamiliar can be a necessary choice.

Unfortunately, a small minority of these co-parents demand a vast majority of the courts’ time. These adults cling to their conflict like a life raft in stormy seas, unaware that the storm is long past.

For these adults, very much like some victims of domestic violence and those parents who can’t allow their children to grow up, the comfort of the familiar is far greater than the risk of the unknown, no matter the pain.

What’s a healthy parent to do? Begin by recognizing how you seek out the familiar and the cost of these choices.

Taking the same route home from work every day may be familiar and comforting, but risks missing out on new scenery and opportunities.

Reading the same bedtime story to your daughter each night likely creates the comfort of routine, but misses out on a million other stories that might be even better.

Recognizing these choices doesn’t mean giving them up, but can bring to light new alternatives you’d never before considered.

If you discover that you’re clinging to familiar habits and relationships that cause you pain, it’s time to talk to someone you trust about why this might be so. Get some objective feedback about why you keep a job where the boss is mean, why you can’t change an unhealthy diet or give up a destructive addiction.

Familiar is easy. Change is hard, but sometimes enduring the pain of change is worthwhile.

And if you recognize that you’re stuck in a destructive relationship, scared to escape violence or abuse or unable to put down your weapons and walk away from the war, ask for help. Seek out a professional who has time and resources, patience and expertise to help you break out of a destructive orbit, to risk the unfamiliar and create new and healthier relationships. Take the chance of discovering that there are healthier ways to live.

Do this now, if not for yourself, then at least for your children so they can grow up, proud to discover your face in the mirror.

Dr. Benjamin Garber is a child psychologist in Merrimack. To order his latest book, “Keeping Kids Out of the Middle,” or to reach him with comments and questions, call 879-9100 or visit www.healthyparent.com. Copyright 2009 Benjamin Garber, all rights reserved.