Not the parent, and I don't have sources handy, but just from some things I've read:
When hiring decisions are made, hiring managers will often prefer men with families, because they will generally stick with the company longer because it's riskier to change jobs with a family to support. This doesn't work for women; hiring managers will be less likely to want to hire a woman of child-bearing age because they're afraid she'll get pregnant and suffer productivity losses as well as take maternity leave. They also assume that a woman with children will be less attentive to work due to child care duties. They assume that men will be less affected by this because, while things are indeed changing, the default assumption is that men will prioritize career over child-rearing, while women will choose the opposite.
I guess, as a man, I feel the expectation is quite the opposite. Namely, that a female in my position would be excused more often to take care of child duties, while my employer would think I'm just being lazy if I told them I wanted to take extra time to care for my child.
In my mental model (note: this is not what I would do, but what I imagine others would do), a woman saying she needs to go home because her baby needs her would be seen as a responsible woman, because a baby needs breastmilk and its mother provides that, whereas, if a man said he needed to go home consistently, the boss would think he's irresponsible, because -- as a man -- his baby doesn't strictly need him, and thus he is better serving his family at work.
But I understand your viewpoint; it just didn't occur to me. It seemed obvious to me that men, due to male biology, were more likely to be forced to work longer hours in order to be seen as being as responsible as an otherwise equivalent woman. Although, I guess today, formula is quite popular. Well regardless, I'm not always the best at understanding how others would react to things.
When hiring decisions are made, hiring managers will often prefer men with families, because they will generally stick with the company longer because it's riskier to change jobs with a family to support. This doesn't work for women; hiring managers will be less likely to want to hire a woman of child-bearing age because they're afraid she'll get pregnant and suffer productivity losses as well as take maternity leave. They also assume that a woman with children will be less attentive to work due to child care duties. They assume that men will be less affected by this because, while things are indeed changing, the default assumption is that men will prioritize career over child-rearing, while women will choose the opposite.