I'm sure biology has something to do with it but that's another simplistic assumption that hasn't been adequately tested (and is convenient for some to believe), and there's a lot of evidence that immense societal pressures push women to do the majority of the work around the home (and that basically tell them that's their responsibility.)
There are other, more equitable ways to sustain civilization besides having the women stay at home and rear children but it would require sacrifice from men that honestly, most seem unwilling to make. Or worse, men aren't cognizant of the full extent of the sacrifices that their partners are making for the family.
I say this as a gay woman that has dated men and am finding negotiating responsibilities and compromises in a same-sex relationship eye-opening to the mostly hidden inequalities in the ways hetero partners relate to each other and divvy up responsibilities. It's the little things that add up -- the assumption about who will pick up the kids from day care [[if a child is in daycare, the parents are presumably both working.. but why are there so many more moms picking up the kids than dads?]], who does the grocery shopping that week, who does the laundry... the default is too often the woman. There might be men on HN that read this that are very good to their partners and try very hard to create an equitable household and feel that this comment is unfair or doesn't reflect their own home situations. That may be true, but the chances are that if you took a very careful accounting over time and paid attention, you'd see a pattern that skews toward particular heteronormative conventions. It's just incredibly hard not to let our society's very rigid and prevalent gender roles creep into our relationships. I have a friend who considers himself a feminist and he is the one that is more vocal and careful about sharing chores than his wife. Why does that seem so noteworthy and laudable? If things were really fair, shouldn't that be more normal?
And I say this understanding that it's not all gravy for men either -- the expectations that are associated with being a man are often unfair and also cause unhappiness. Honestly, though, when it comes to things like resource and opportunity distribution, these differences tend to favor men (for instance, there's evidence that gender roles and expectations play a big part in the salary disparity between men and women.) I'd say that's a major problem. The article's author says that many women would rather work part-time and raise children and find that a fulfilling life. That's wonderful. The question I'd like to raise is, if they had the opportunity to work full-time or even do something demanding like a startup and still feel like they had the time and energy to raise their children well (perhaps because their husbands are willing to work part-time and pitch in more toward raising the kids), would they rather take that option? And if so, what can we do as a society to help make that a reality?