Who's the Favourite?: Understanding Our Sibling Relationships as Adults

by Catherine Carr

The first book to explore the joys and complexities of adult sibling relationships
'Whether you're a sibling or an only child, Catherine Carr's book will leave you wiser and feeling more at home in the world.' Oliver Burkeman

For most of us, our sibling relationships are the longest we will ever have. Whether loving or fraught, competitive or codependent, these bonds shape us in lasting ways.

In this heartfelt, judgment-free book, Catherine Carr invites us to look at our brothers and sisters beyond the labels assigned in childhood. Combining real-life stories with expert insight, she explores birth-order stereotypes, favouritism, trauma, blended families, only children, siblings with additional needs, and the pain of estrangement and bereavement.

These relationships are rarely straightforward but thinking about them more deeply may help us better understand ourselves and the world around us.

*Interwoven with candid interviews with sibling pairs taken from her hit podcast, Relatively, such as Chris and Xand van Tulleken, Johnny and Lillie Flynn, Nick and Gill Hornby, Manni and Rueben Coe, and more*

'Truly enlightening, charming and moving.' Jane Garvey

'Brilliant.' Dame Jenni Murray

'Hilarious, moving and fascinating.' Chris and Xand van Tulleken

Genres: Nonfiction, Psychology

336 pages, Kindle Edition

Published March 19, 2026

Reviews

[Kathryn · Rating 4 out of 5]

I'm an absolute sucker for any book with a focus on siblings.

8/10 - I just wanted even more!

[Teresa · Rating 5 out of 5]

I came across this book on a random visit to the library. Prior to seeing it, I had never considered how the sibling dynamics influenced character development. Also, as a middle child, I suspected this book would validate a lot of my “middle child frustrations”.

What it actually did was force me to see my siblings as individuals with their own experiences instead of just people connected to me. It forced me to confront my own perceptions about birth order stereotypes and think about how truly unique sibling relationships are. It also shed light on how sibling relationships in media portray these stereotypes. For example, the Fisher’s blatant favoritism and Belly choosing Conrad feeding into Jeremiah’s feelings of inadequacy (in The Summer I Turned Pretty).

The book is grounded in research and explores complex (and often nuanced) issues like estrangement and grief. I like that the author didn’t ignore the fact that a lot of the already limited research in this area is from Western households.

[Donna Williams · Rating 3 out of 5]

I’m the youngest of 3 sisters and I’ve always been fascinated by discussions around birth order. The author introduced some new concepts to me: the idea of vertical vs. horizontal sibling relationships and something called “glass” siblings. It was interesting to know that when there is a loss of a sibling, the grief of the sibling(s) left behind is often not addressed and not tended to. The focus tends to be on the parents when there is a loss of a child. That was eye opening for me!

I enjoyed when the author shared specific details and dynamics within her own family. I would have wanted more specific scenarios and less passing references to studies done by “Dr so and so” and what “Dr so and so” said. My overall impression is that I should check out Catherine Carr’s Podcast “Relatively” - I might enjoy that even more than this book.

[ts_review · Rating 2 out of 5]

DNF after 65ish%

I picked up this book after fighting with my sister and wanting to see if there are insights here that would help me understand her and our sibling dynamics better.

But, I found Carr’s writing style to be haphazard and tedious. Her style is name-dropping a psychologist or researcher, adding a line or two explaining their study, and before the reader has the chance to fully engage with the study, the outcomes and the significance, Carr moves on to name-drop another doctor/psychologist/researcher/etc.


And then there are so many sections where she references the same doctor/psychologist/researcher she mentioned 5 pages ago, but because it's under a new subsection she mentions them again from scratch which means including the name of their book, their research, etc again.

This book reads more like a messy scrapbook, bursting with data, literary quotes, random memoir-ish asides, and an entire section on vocabulary that made me go "why?" and, "well, that's certainly a choice...."

[Becky of Becky's Bookshelves · Rating 5 out of 5]

Who's the Favorite? The Loving, Messy Realities of Sibling Relationships By Catherine Carr is a wonderful, insightful, and very readable book about sibling relationships. I am especially close to my sisters and brothers who are near to my age. I love how our relationships have evolved over the years. I enjoyed reading the author's thoughts, research and humor about siblings.

I especially appreciated the chapter on having a special needs sibling, roles and labels, and on loosing a sibling. I felt like I was having coffee with the author and came away appreciating my siblings so much more. I highly recommend.

I was gifted a copy and not required to write a positive review.

[Idy · Rating 4 out of 5]

The truth is that sibling relationships are one of the strongest bonds any individual can have because they form a great way of shaping who you are, and this begins from the childhood years up until the adult life.

The differences are to be embraced and understood for a healthy relationship among siblings.

[Patricia · Rating 5 out of 5]

Really interesting. I wish it had gone deeper into some of the studies cited (very curious about the methodology on some), but I understand the book is trying not to be too technical. I learned a lot.

[Diane Strachan · Rating 4 out of 5]

A thought provoking look at siblings and the science behind birth order, and how much truth there is behind the stereotypes of being the eldest, middle or youngest. I found it pretty interesting and it made me think about the family dynamics in my own family and in other families I know.

[Katie Salmon · Rating 5 out of 5]

A fascinating and empathetic look on sibling relationships in all shapes and sizes.

[Jennifer · Rating 5 out of 5]

Really enjoyable, comprehensive, full of interesting stories and scientific findings. Well written and full of heart ❤️

[Mandy Bundock-Simjian · Rating 5 out of 5]

AMAZING

[Yvona]

audio summary

[Ruth Stitt · Rating 5 out of 5]

Loved!

I could not put this book down. So interesting, so well written, so compelling. Very insightful. Will be recommending to all of my friends!

[jo 💫 · Rating 3 out of 5]

some heartbreaking quotes and new perspectives for sure, but wasn’t quite what i had hoped it’d be

[Anna McGrath · Rating 4 out of 5]

Very thought provoking, especially to your own sibling circumstances. I’ve also picked up a range of books, which were used for reference purposes, that I now want to read.

[Dara · Rating 3.5 out of 5]

3.5 Stars. I went into Who’s The Favorite by Catherine Carr expecting a book about sibling rivalry. It is actually more about sibling relationships and how they effect entire lives. It is about all types of siblings including step siblings, half siblings, growing up with a disabled sibling, and experiencing the death of a sibling, with not that much about favoritism. I enjoyed the references to pop culture siblings. I would have liked more stories about siblings and interviews about the sibling experience.

[Charlotte · Rating 5 out of 5]

Fantastic. Insightful, intelligent, funny and deeply moving, this is a totally charming book that will gently lead you to consider sibling relationships in an entirely different light.