Boundaries per se are not wrong. Our lives are always defined, ying & yang-like by the existence of the "Other;" that which is not us. And we can get particularly refined in defining the Other; in fact, we are superb hair-splitters:
Agnostic vs. Religious
Other Religions vs. Christianity
Catholic vs. Protestant
Baptist vs. Episcopalian
High vs Low Church
Where do we get this habit of pigeon-holing, of laying out boundaries? Well, in part, it is hardwired into us. Part of our success as a species is that we have evolved to identify patterns - patterns in sound (speech and music), patterns in our environment (weather and seasons), patterns of danger, patterns everywhere.
Children start identifying patterns from the youngest age and it is what gives them the capacity to startle us. The patterns they think they see do not match the patterns we as adults are accustomed to seeing.
I recall being very startled by one of our kid's questions. I don't remember the exact circumstances, but they were perhaps three or four and I think we had spent the day with a group of friends in Australia. Most the people were Australian but there were a couple of Asian families as well. On the way home afterwards, one of our kids asked me, "Daddy, are we Asian?" Well, since we are Caucasian, this came as something of a surprise. I explained the difference between the appearances of Caucasians and Asians. At first I thought this was just a confusion owed to the similarity of the words. Talking it through though, it became apparent that that was not the issue at all.
Our child had noticed subtle dynamics in the conversation. The pattern that they had observed was that the Asians and the Americans were the ones different to this group of Australians. If we and the Asians were the different ones, then did this make us Asian? All perfectly logical once you think it through from a child's perspective, but yet another example of how different and fresh their perspective can be. And how differently they can interpret what and where the patterns and boundaries are.
All this effort to identify patterns and the categories that go with them are predicated on taking control of your environment. The more you are able to identify patterns and categories that are meaningful, the more you can begin to predict. Dark clouds - probably rain. Slithering animal - probably snake. Shouting and waving of arms - probably angry. Each prediction then becomes the basis for some action to encourage a good outcome or avoid a bad one.
One of the most pernicious trends of the past fifty years has been the sanctioned pigeon-holing of people based on one-dimensional attributes, usually race, ethnicity, gender or religion, each meaningless without context. The boundaries around which we build our assumptions only take on meaning when weighted against one another and in context. It is easy to create scenarios that highlight just how dramatic the differences in context can be. You are walking down the street late at night in a rough part of town and four or five young fellows emerge from an alley and walk towards you. With nothing more than that, you are probably quickly kicking into fight or flight mode. Change one thing and you are in an entirely different situation. Instead of emerging from a dark alley they are emerging from a church with a Youth Meeting Tonight sign at the front.
It is unavoidable that we teach our children boundaries and differences; and we often do it by accident.
Child: Daddy, I don't like him.
Parent: Why not?
Child: He smells and his clothes are all dirty.
Parent: Why do you think that is? Maybe they can't afford a washer and dryer and his clothes don't get cleaned that often.
With the best of intentions of getting your child to understand the context and to see that some things might be beyond a persons' direct control, you are also accidentally setting up the expectation that poor people are smelly people. Acchh! Parenting is the most complex task ever undertaken.
So what can be done about boundaries and stereotypes and categories. I don't think the answer is in trying to hide that there are differences between peoples but rather to give a context and show that some of those differences are important and some are not and that it is the differences that makes things interesting. To teach them that whatever the stereotypes might be, you need to approach a person as a person and not some statistical sampling - to give them the respect they deserve and to let them show you they are worthy of friendship rather than shutting that door through assumptions that may be accurate on average and can never be fully accurate for a data set of one.
There are thousands of truly wonderful children's stories that tell the tale of children and people coming together, many times unexpectedly, to overcome mutual suspicions arising from assumptions (or raw ignorance) about gender, race, age, ethnicity, religion, wealth, class, culture, accent, language, country of origin, etc. The following are some stories where friendships are forged across the boundaries of age, race, religion, class, etc.
A Splendid Friend Indeed by Suzanne Bloom Suggested
Sneetches and Other Stories by Dr. Seuss Highly Recommended
Pocahontas by Leslie Gourse and illustrated by Meryl Henderson Suggested
When Jessie Came Across the Sea by Amy Hest and illustrated by P. J. Lynch Highly Recommended
Great Wolf And the Good Woodsman by Helen Hoover and illustrated by Betsy Bowen Highly Recommended
Rikki-Tikki-Tavi by Rudyard Kipling and illustrated by Lambert Davis Highly Recommended
Frog and Toad Are Friends by Arnold Lobel
Secret of the Peaceful Warrior by Dan Millman and illustrated by Bruce T. Taylor
The Gardener by Sarah Stewart and illustrated by David Small
Eight Cousins or the Aunt-Hill by Louisa May Alcott
Indian in the Cupboard by Lynne Reid Banks and Brock Cole Highyl Recommended
Keeper Of Soles by Teresa Bateman and illustrated by Yayo Suggested
Hope Was Here by Joan Bauer Highly Recommended
A Little Princess by Frances Hodgson Burnett and illustrated by Tasha Tudor Highly Recommended
Granny Torrelli Makes Soup by Sharon Creech and illustrated by Christopher Raschka Suggested
Despereaux/the Tale Of Despereaux by Kate DiCamillo Recommended
Because of Winn-Dixie by Kate DiCamillo Highlt Recommended
Chicken Boy by Frances O'Roark Dowell Suggested
The Hundred Dresses by Eleanor Estes and illustrated by Louis Slobodkin Recommended
Once upon a Marigold by Jean Ferris Recommended
The Double Life of Pocahontas by Jean Fritz and illustrated by Ed Young Suggested
Lily's Crossing by Patricia Reilly Giff Recommended
Dark Water Rising by Marian Hale Suggested
Jessica by Kevin Henkes Suggested
Hoot by Carl Hiaasen Recommended
Journey to the River Sea by Eva Ibbotson and illustrated by Kevin Hawkes Highly Recommended
Martin Bridge Ready For Takeoff! by Jessica Scott Kerrin and illustrated by Joseph Kelly Suggested
The Jungle Book by Rudyard Kipling and illustrated by Jerry Pinkney Highly Recommended
Rikki-Tikki-Tavi by Rudyard Kipling and illustrated by Lambert Davis Recommended
Last Days of Summer by Steve Kluger Suggested
Buddha Boy by Kathe Koja Suggested
The View from Saturday by E. L. Konigsburg Suggested
Marven of the Great North Woods by Kathryn Lasky and illustrated by Kevin Hawkes Suggested
To Kill a Mockingbird by Harper Lee Highly Recommended
Ella Enchanted by Gail Carson Levine Highly Recommended
Ronia, the Robber's Daughter by Astrid Lindgren and illustrated by Alfred Lindgren Recommended
From Anna by Jean Little Recommended
Gathering Blue by Lois Lowry Recommended
Gold Dust by Chris Lynch Suggested
Anne of Green Gables by L. M. Montgomery and illustrated by Jody Lee Highyl Recommended
Gentle Ben by Walt Morey and illustrated by John Schoenherr Recommended
The Mzungu Boy by Meja Mwangi Suggested
Shiloh by Phyllis Reynolds Naylor Highly Recommended
Chicken Sunday by Patricia Polacco
Bread And Roses, Too by Katherine Paterson Suggested
Bridge to Terabithia by Katherine Paterson and illustrated by Donna Diamond Recommended
Pink and Say by Patricia Polacco Suggested
Mrs. Katz and Tush by Patricia Polacco Suggested
Elijah's Angel by Michael J. Rosen and illustrated by Aminah Brenda Lynn Robinson Suggested
Holes by Louis Sachar Highly Recommended
Lizzie Bright and the Buckminster Boy by Gary D. Schmidt Suggested
The Sign of the Beaver by Elizabeth George Speare Recommended
The Witch of Blackbird Pond by Elizabeth George Speare Recommended
Charlotte's Web by E. B. White and illustrated by Garth Williams Highly Recommended
Crow Boy by Taro Yashima Suggested
The Prince and the Pauper by Mark Twain Recommended
Adventures of Huckleberry Finn by Mark Twain and illustrated by Donald McKay Highly Recommended