THE first time it happened was before my second son was even born. I was chatting to an elderly lady in the Post Office queue when she smiled at my bump and asked what I was having.

“A boy,” I said. “A brother for my two-year-old son Ruadhán.”

“Never mind,” she replied, with a wink. “You’ll just have to try again for your little girl.”

I was so taken aback, I could only stammer that I just wanted a healthy child.

Since becoming a mum of “only” sons after my second, Donnacha, was born 15 months ago, I’ve grown wearily familiar with the assumption I must be desperate for a daughter.

The comments about wanting to buy pink clothes, have someone to go shopping with, and have a “best friend” are incessant. Even Prince Harry has said that he would love to have a girl and Meg’s not even in her third trimester yet.

But at least I’m in good company. TV presenter Cat Deeley, who last summer gave birth to her second son with husband Patrick Kielty, made it clear that she had no intention of now trying for a girl.

“No, I think I’m done,” she said in an interview. “I love my boys.”

Friends with sons sympathise. Hannah, a mum of two boys with a third baby (gender unknown) on the way, says: “I keep being asked whether I’ll be disappointed if it’s not a girl, and if we’ll go for a fourth if it’s another boy.”

And Laura, who also has two sons, is sick of being told “a daughter’s a daughter for the rest of your life, a son is a son until he takes his wife”, as if her boys will grow up to love her any less than a girl would.

On the flipside, parents of all girls are subject to the same insistence they must crave a son. James, a dad of four daughters, gets called “Barbie Balls” by the guys at the gym where he works out. Thick-skinned, he laughs it off, but the implication is that he’s less of a man without a son.

According to psychotherapist Jane Barnfield-Jukes, founder of counselling service The Practice, we’ve been socially conditioned to believe the “perfect” family must have both genders represented.

“Therapists call it the Disney effect, as research suggests we are perpetuating the myth of the ideal family as having at least one of each sex, otherwise its dynamic is lacking in some way,” she says.

“It’s a relatively modern commentary, because in the past families were bigger so were more likely to have a mix.”

And, according to Jane, rather than simply valuing children for who they are, society expects them to perform specific roles according to their gender.

“Whether that’s to be a doll for Mum to dress up, or a mate for Dad to kick a football about with, we’re pigeonholing them before they’re even born,” she explains. “These comments are usually made without malice, but it’s thoughtless to make a parent feel they’ve failed in some way and it can be damaging if that sense of failure filters down from the parent to the child.”

Had either of my sons been a girl I’d have been thrilled, but I was equally delighted they were boys. I wept tears of joy at my 20-week scan last April when I spotted Donnacha’s little boy bits on the screen. I was delighted Ruadhán would have a brother, especially with just over two years between them.

Yet when you have a single-sex brood, it’s very hard to convince people you’re genuinely happy with that dynamic. And, ironically, if you admit you’re not over the moon, there’s a backlash.

When model Danielle Lloyd revealed in August that she was planning gender selection to guarantee a longed-for daughter after four sons, she was trolled and called “selfish” and “disgusting”.

But why shouldn’t she want a girl? It’s her prerogative to feel that deep-rooted desire, just as it’s mine not to.

I live in a world of Thomas The Tank Engine and Marvel Superheroes, and you know what? I love it.

If I crave female company I have friends, a god-daughter and my own mum to fulfil that need. And who’s to say mums of boys won’t find their little one is into dolls and unicorns?

Train-mad Ruadhán will only eat pink ice cream, while my friend Carly’s son’s pride and joy is an old doll’s house he inherited from his big sister.

I had children to have children, not because their gender was in any way important. I revel in my sons’ innocence, their mischievousness, playing imaginary games and cuddling up for stories at bedtime.

None of the joy I feel being their mother has anything to do with what sex is on their birth certificate.

I’m proud to be a mum of “just” boys. They’re more than enough for me.