Kristin Cavallari's Instagram fans are outraged by her "skinny" kids.

A week ago, Kristin Cavallari posted a picture on Instagram of her husband and two little boys, three-year-old Camden, and two-year-old Jaxon, playing at the beach.

Even though we’re not in the states, were still celebrating ???? hope everyone has a fun and safe 4th! #MyGuys

A photo posted by Kristin Cavallari (@kristincavallari) on Jul 4, 2016 at 8:18am PDT

And the Internet got really, really pissed off.

Comments included: “Seeing pictures of your boys and how they look is a bit shocking to see.”

“Sorry that the truth hurts. But the poor child’s bones are popping out. Instead of getting mad at everyone for being alarmed look in to the child’s diet,” another added.

Others weighed in: “I understand you live a very strict dietary lifestyle but these children are very obviously nutritionally deficient. A great pediatrician and dietician would be so helpful.”

And another begged: “Please look into feeding your babies.”

Cavallari has since deleted the comments and blocked a number of users.  She wrote on Instagram: “Just blocked the most people I’ve ever blocked in my entire life. Happy 4th hahaha.” 

When my little man, Jax, actually stops for 2 seconds AND cuddles with me, I'm in heaven ❤️ #AlwaysOnTheMove A photo posted by Kristin Cavallari (@kristincavallari) on Jul 6, 2016 at 1:22pm PDT

When I saw this photo, 'concern' was the furthest thing from my mind. My first response was simply "Ha, that shot could be straight out of our family photo album."

Bony backs, knock-knees, tiny shoulders and sharp elbows. My little brother's party trick used to be to suck in as hard as he could, and make his entire stomach disappear. To this day, I have no idea where his organs were housed for at least the first 1o years of his life.

When my twin sister ran her first cross country in kindergarten, her sports skirt, which was in the smallest size, ended up around her ankles. In Year Three she weighed 19 kilos and looked frankly absurd in her school uniform.

We were weird looking kids. Image supplied. 

As my Nan affectionately put it - we were "scrawny". We had aunties and uncles ask mum if were okay. Mum would laugh, because her family, and indeed Dad's family, had looked exactly the same as kids.

This week, we were yet again reminded that mothers cannot win. Kristin Cavallari's crime? Having skinny kids, who she dared take to the beach on the 4th of July.

Four years ago, it was another mum of two boys, copping the opposite criticism.

Chrissie Swan was shamed because her children were allegedly "too fat". After posing for a photo shoot with The Australian Women's Weekly, readers expressed their 'concern' that Swan was a bad role model for her sons. One commenter wrote: "Her sons already look fat, like mother, like sons." And another said: "You are what you eat and Leo is not cute, he's absolutely huge!!! Shame on you Chrissy [sic]."

As someone without kids, who hopes to have them one day, I am already well and truly fed up with the unrelenting condemnation we subject mums to. And the most disappointing part? It overwhelming comes from other mothers.

I cannot help but wonder; are these commenters really concerned? Are they sitting at home, riddled with anxiety, rocking back and forth, because they genuinely think that Cavallari's two boys aren't getting the nutrients they need? Are Aussie mums truly distressed, because Chrissie Swan's two sons are a little chubbier than your average toddler? Do they, sincerely, have the best interests of the child at heart?

Happy Birthday baby girl ???????????? We all love you so much ???????????? X @davidbeckham @brooklynbeckham kisses from mummy X

A photo posted by Victoria Beckham (@victoriabeckham) on Jul 10, 2016 at 1:27am PDT

Just yesterday it was Victoria Beckham kissing her daughter on the lips.

My theory is no. They are not all that invested in other people's kids. The judgement comes from a deep place of insecurity - an underlying fear harboured by all mums, that they themselves are not doing a good enough job.

But the reality is that most mums are just doing their best.

We insist on making women feel like bad mothers. Post continues below. 

So, is Cavallari starving her kids? No chance. They are a product of genetics, just like Chrissie Swan's children. Some family photo albums are full of bony backs and knock-knees, and others of chubby faces and round bellies. I'm not sure how much more research has to be done into how weight is not a direct indication of health, before we actually start to believe it.

We must start to trust fellow mums, because all the criticism achieves is a perpetual and detrimental cycle of insecurity.