Like many couples, we both work full time. We work roughly the same number of hours at similarly intense and stressful jobs. Yet, these days, I find myself taking on the bulk of the homework duty. With three children and maths, English and Chinese, that’s a lot of homework. I tell myself it’s because I’m good at it. After all, I am an educator. However, let’s be honest, even if I wasn’t, I’d probably still be the one who does it.

READ MORE: Unhelpful husbands a factor in female CEO shortage in Hong Kong

That’s because mums on average take on more childcare duties than dads. A new study released in the Journal of Marriage and Family followed nearly 200 couples in Ohio State University’s New Parents Project over a period of years. Some 95 per cent of these couples said they wanted an egalitarian marriage, to split the housework and childcare equally.

Then they had a baby. As soon as that happened, the 50/50 deal went out the window. By the time the baby was nine months old, the mothers were putting in 37 hours of housework and childcare each week on top of working full time. The fathers, on the other hand, were only putting in 24 hours. A 13-hour difference may not sound like much but they can mean the difference between going for that next big project or taking a back seat.

It’s little wonder only 5 per cent of Fortune 500 CEOs in the US are women. Globally, women represent only 10 per cent of board-level positions, despite making up 40 per cent of the workforce. Here in Hong Kong, only 4 per cent of the CEOs of listed companies are women.

READ MORE: Forget about gendered careers, women’s workplace equality is a necessity in Asia’s aging population

All this is depressing. Yet, when I step into the classroom, I am continuously amazed by the sharp and insightful observations my female students come up with. Earlier this week, I led a group of spirited female students to debate against women from all around the world in the BBC 100 Women global debate. I watched as these girls ripped through questions like “Does a woman need to act like a man in order to lead?” They said things like, “You don’t have to wear pants in order to be a leader. All you need is your strength of will and, when it comes to that, women can easily match up to men.”

READ MORE: Every day is a day nearer the goal of gender equality in Hong Kong’s corporate world

Hearing these young girls speak their minds with gusto and passion, I was never more optimistic about the future of women. At the same time, I couldn’t help but wonder: if this is the way girls start off – full of energy and the determination to go out and conquer the world – then why don’t more of them do just that? What happens along the way that stops them in their tracks?

Homework duty, that’s what. It’s the automatic expectation that women would and should take on the bulk of the child rearing, no matter how many hours they are working. Whether it’s making the cupcakes for the class birthday party or checking over spelling on a rainy Sunday afternoon, people still think of these activities as mum activities. Well, they’re not. They’re everyone activities.

So, after my husband asked the question, I turned to him and said, “I didn’t drop the ball on the math. Honey, we dropped the ball.”

Kelly Yang teaches writing at The Kelly Yang Project, an after-school centre for writing and debate in Hong Kong. She is a graduate of UC Berkeley and Harvard Law School. www.kellyyang.edu.hk