The Science of Sibling Jealousy and How to Help Your Kids Adjust

, ,

Understanding Sibling Rivalry: An Evolutionary Perspective

Picture this: You’re sitting on the couch, holding your newborn, when your toddler suddenly runs up and starts demanding your attention—maybe they cry, try to pull the baby away, or even climb into your lap. It might feel baffling or even frustrating, but this behavior is actually rooted in something much deeper than simple attention-seeking.

Sibling rivalry—competition between siblings for a parent’s attention and resources—isn’t just a modern parenting challenge. In fact, research shows it’s an age-old behavior that has roots in our evolutionary past. A fascinating study by Sybil L. Hart (2018), published in Evolutionary Behavioral Sciences, reveals that even babies under one year old can experience sibling rivalry when a new baby arrives in the family.

This study not only helps us understand why children feel this way but also shows us how these behaviors were adaptive in ancient times. While these instincts may no longer be about survival, they still play a role in family dynamics today. By understanding the evolutionary basis of sibling rivalry, parents can respond with empathy and take practical steps to foster harmony between siblings.

Sibling Rivalry: An Ancient Adaptation

Hart’s study highlights that babies as young as nine months old can show “jealousy protest” when a parent’s attention shifts to someone else—especially a new sibling. This isn’t just a phase or bad behavior. It’s an instinctive response tied to survival. For our ancestors, resources like food and caregiving were limited, and competing for these essentials was crucial. Jealousy protest—clinginess, crying, or acting out—helped ensure an infant stayed close to their caregiver and maintained access to critical resources.

What About Older Siblings?

While this research focuses on infants, the same principles apply to older siblings. A toddler or even a school-aged child might react to a new baby with jealousy, resentment, or regression. They may act out, whine, or become extra clingy, as they interpret the newborn’s arrival as a threat to their own standing in the family. The same evolutionary need for connection and exclusivity that drives an infant’s jealousy can manifest in older children, albeit in more complex ways.

What Can Parents Do?

Knowing that sibling rivalry is natural can help parents respond with understanding and practical strategies. One highly effective approach to strengthening your relationship with each child and potentially reducing sibling rivalry, is Child Directed Interaction (CDI).

What Is Child Directed Interaction?

Developed as part of Parent-Child Interaction Therapy by Sheila Eyberg, CDI focuses on improving the parent-child relationship through play. In CDI, the child takes the lead in choosing and directing play activities, while the parent provides focused attention, positive reinforcement, and avoids criticism or commands. Just reading the description you can tell how rewarding this parent-child experience would be to your child. Bonus: Once parents get comfortable with child directed play they often find the experience very rewarding also.

Here’s the basics of how to use some CDI skills at home:

  • Let Your Child Lead: Allow your child to choose a safe play activity (e.g., drawing, building blocks) and follow their lead without directing or correcting.
  • Use Positive Reinforcement: Give specific praise, such as “I love how you’re stacking those blocks so high!” This reinforces their efforts and creativity.
  • Narrate Their Actions: Use “behavioral descriptions” to describe what your child is doing, such as, “You’re drawing a big sun with yellow rays.”
  • Reflect Their Speech: Repeat or paraphrase what your child says to show you’re actively listening. For example, if they say, “I built a tower!” you might respond, “Wow, you built a tall tower!”
  • Avoid Criticism or Commands: Focus on enjoying the activity without giving instructions or correcting mistakes. As long as your child is being safe, you can ignore little misbehaviors; don’t give them attention.

Just 10 minutes of child directed play a day can often significantly improve a child’s sense of connection and security.

Additional Strategies to Reduce Sibling Rivalry

  1. Acknowledge Their Feelings
    Let your child express their emotions, even if they seem difficult or irrational. Saying, “It’s okay to feel upset,” or “It’s hard to share Mommy’s attention” can go a long way in helping them feel understood.
  2. Make the Older Child a “Helper”
    Involving older siblings in caring for the baby can give them a sense of pride and inclusion. Let them fetch diapers, sing to the baby, or help during bath time. Remember to give a simple praise for this helpful and safe big sib behavior.
  3. Celebrate Their Individuality
    Remind your older children of the special role they play in your family. Highlight their unique accomplishments and let them know they are loved for who they are.
  4. Stick to a Routine
    Children feel safe with predictability, especially during times of change. Keeping consistent meal times, bedtime routines, and playtimes can help them feel more secure.

Why a Little Extra Attention Matters

Sibling rivalry is not a sign of bad parenting—it’s a natural part of growing up in a family. By understanding its evolutionary roots and addressing your children’s need for connection, you can help reduce rivalry and foster positive sibling relationships. As Hart’s research highlights, even a little extra attention can help children feel secure and less inclined to compete for your love and care.

By carving out moments of one-on-one time, incorporating strategies like child directed play, and validating your children’s feelings, you’re giving them the tools they need to feel confident and valued. And in doing so, you’re creating a family environment where sibling bonds can thrive.

Participate in discussions on related topics in Mamapedia:

Book suggestions for siblings to be

Advice on siblings fighting a lot

I need advice on talking to my 4 year old about expecting a new sibling.

How to Reward a Helpful Sibling

Siblings fighting

New siblings two years apart

Citation

Hart, S. L. (2018). Jealousy and attachment: Adaptations to threat posed by the birth of a sibling. Evolutionary Behavioral Sciences, 12(4), 263–275. https://doi.org/10.1037/ebs0000102

Eyberg, S. M., Boggs, S. R., & Algina, J. (1995). Parent-child interaction therapy: a psychosocial model for the treatment of young children with conduct problem behavior and their families. Psychopharmacology bulletin31(1), 83–91.

For more information on Parent-Child Interaction Therapy (PCIT) contact PCIT.org

Start the discussion at forum.mamapedia.com