When I was nine years old, I remember filling out a "when I grow up I want to be…" worksheet at school. It was shaped like a cloud and I answered with "Dad".

I thought then that I'd probably grow up to live a suburban life as a dentist, with a wife, three golden retrievers, and seven kids.

But then I realised I hated teeth, didn't like dogs, and was very gay.

I still longed to be a dad, of course. But that involved a wife, a big secret, and a very unhappy life. You know, the stuff fairytales are made of.

And so I never expected to become a father.

Then, the world changed. Not merely my own, but the world "out there".

All of a sudden, I started to question myself

Celebrities started coming out. Couples got civil unions, and others even started families through adoption. Our stories were told on television.

And then when I was 16, the state of Massachusetts, the one next door to me in New Hampshire, legalised gay marriage.

It wasn't until a few months before my boy-girl twins were born that I started to question my abilities as a father. ( Supplied: Sean Szeps )

By the time I graduated from university and moved to New York, becoming a father as an openly gay guy was no longer an impossible dream.

When I fell madly in love with Josh, a smart-ass Aussie in Manhattan, we did what soulmates have always done: we tied the knot.

Then we did what had been impossible for most of human history. Thanks to IVF and surrogacy in the United States, we became two dads.

I knew this journey to fatherhood would be challenging, but I didn't question how great I'd be at it.

It wasn't until a few months before my boy-girl twins were born, when others reminded us of our difference (inadequacy?) or asked how we would survive "without a mother in the house", that I started to question myself.

'Where's mummy?'

It started well before the birth, as I crossed out "mother's name" on hospital forms and gift registries. Every legal letter, financial statement, and parenting article was a casual reminder of just how new this all was.

When our twins were born, we got an "I Love My Mum!" baby onesie as an accidental gift that had wrapping paper with a mum and dad cartoon on it.

Airport staffers, waitresses, and librarians all asked the same question: "Where's mummy?"

Then we moved to Sydney. The local mothers group wouldn't have me (although I know this is a problem facing stay-at-home heterosexual dads too).

Fair enough, I'm not a mother.

But even the all-female groups that met at the local parks seemed uncomfortable with my presence. I had no choice but to power through the most challenging early months of stay-at-home parenting alone.

When I was in public with wailing infants, women frequently came up to me to say that I should go home and thank my wife for looking after the kids 24 hours a day.

When I was in public with wailing infants, women frequently came up to me to say that I should go home and thank my wife. ( Supplied: Sean Szeps )

My husband and I handled it. We were proud to be forging a new path. We knew we fell into the minority and that these types of things were part of forging a new path.

But that didn't make it any easier. Thousands of years of culture and law were treating us as incomplete.

Who had the answers? Not us

Not just culture and law, but biology. The nurse at the hospital was uncomfortable when we asked if there was any special guidance we needed about how to care for our little daughter's hygiene.

We handled it, but it wasn't easy.

Inheriting a lack of gender parenting roles as same-sex parents was equal parts liberating and disorienting.

While neither of us had traditional mother-father expectations of how we should do things, both of us noticed the ways in which the other fell short. It felt freeing but also more frustrating.

Who should get up at 2:00 AM to feed the babies? Or read to them before bed? Who should clean up their vomit? Change their nappies? Do school drop off?

Who had the answers? Not us. Not anyone really.

This turned out to be a blessing. Our parenting relationship became a question of what we wanted to do, instead of what we needed to do.

It meant analysing our strengths and prioritising what made us happy.

In a word, it's love

I've befriended enough mums along the way to know just how rare that is. I've also picked up from them just how challenging social expectations can be.

Most straight couples, for example, are often left feeling trapped by weak paternity policies and the biological need for women to breastfeed.

We know we are blessed to have grown up during a moment in history when having a family is a widely accepted option for same-sex couples. We aren't naive about how new it is.

But it would feel more legitimate if well-meaning people didn't unwittingly remind us that it's weird.

My dream used to be to become a father. Now, my dream is that by the time my kids have kids, society will still honour the work of mothers, but that the line on the hospital form won't say "mother's name", just "parent".

The world is changing quickly. Women are going back to work sooner, men are more involved in parenting than ever before, and children are surrounded by more diverse examples of what a family can look like.

With this shift comes a change in our understanding of who and what helps to produce healthy and happy humans. It's not pregnancy or body parts that determine if we're capable of being good parents.

It's our ability to show up and be present in our children's lives. In a word, it's love.