Does an only child experience sibling rivalry?

Referring to my daughter as an only child is new concept for me.

When she was an infant, strangers would often ask me if she was my first. And every time the question was posed, it became very real for me that I could potentially have another kid. I got used to the question and started referring to Anna as my first, rather than my only.

I'd never considered having kids until I was in my mid-20s, and it wasn’t until well into my pregnancy that I even considered having a second child. Anna turns four in September, and I honestly just sold her change table earlier this week—despite the fact that she's been potty trained since she was 18 months old. I'd held on to the change table partially out of sentiment and half in hopes of having another baby one day. And while a second child is not entirely ruled out—which is a whole other post of its own—for financial reasons, and, more objectively, medical ones, it seems unlikely that Anna will have a sibling.

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Despite this, I have this theory that my child experiences sibling rivalry, and acts out on it. I can already hear the parents of more than one child telling me that this behaviour isn’t sibling rivalry, that it’s just a matter of my daughter not being able to share. But bear with me.

I see my kid mimicking the behaviour of her daycare peers. What looks like is this: Jessa gets a baby sister, Jessa starts acting out; Anna is around for this and copies the behaviour. It’s not the only time I’ve seen my kid do something like this.

Between the ages of one and two, she went to a small, private daycare where she was much younger than the other kids. An older kid would be going through the “but why?” phase and Anna would bring it home. She’d ask "why" over and over again, not knowing what it meant, but knowing it was what bigger kids did. In a small-scale example of this, the other day she saw a kid sucking her thumb and immediately did the same. Anna has never sucked her thumb (she didn’t even take a pacifier), but seeing another child do it made her curious. If it’s in kids’ nature to copy, than isn’t it likely that this could be happening when it comes to acting out jealousy, attention-seeking, and so on?

Another time I've noticed a change in her behaviour is when my friends bring their babies around. When our baby friend Troy was born, it was a big deal to Anna. Although other kids younger than her had been referred to as “baby”—Baby Noah, Baby Izzy, and so on—they were all so close in age to Anna that by the time they learned to walk they were basically her peers. Anna met Troy when he was a tiny newborn. He’s three years younger than her, so even as he catches up in size (and fully bypasses her in style) he maintains the moniker Baby Troy. I just so happen to babysit Troy on occasion, leaving ample room for jealousy and weird sibling-esque behaviour.

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One evening, Anna was dead-set on Troy sharing her bed, even though he was much too young for this to be safe. I humoured her, with supervision, and it was mere minutes before she was screaming that he was taking up too much space. Earlier on that same visit, Anna had put 15 headbands on his head while he tried to resist. He swatted at her face with his teeny, tiny hand, and she had a fit that he’d hit her. There is something to be said for “siblings” you can return at the end of the day.

Similarly, the one kid she’s hurt at daycare (biting, scratching… nothing I'm proud of) is a girl I often would comment was "so nice" or "so cute." Maybe this is unrelated, but with a large class (and the reality that this little girl is so nice) I have a hard time thinking Anna was not taking out some version of sibling rivalry on her.

What do you think: Do only children show traits of sibling rivalry? 

Tara-Michelle Ziniuk is a Toronto-based queer mom to a preschooler. She started off as a single-mom-by-choice, and now co-parents. You can read more of her posts here and follow her on Twitter @therealrealTMZ.