My parents were married after meeting in college, a few years after the end of World War II. Dad was going to be a Captain of Industry and Mom was going to teach school for a little while and then raise a family. They had three kids, of whom I am the youngest.
A funny thing happened: it turns out that my dad was constitutionally more nurturing than my mother. If you needed a boo-boo kissed or a lap to sit in, you went to Dad, and if you were sick at four in the morning, the one who was suddenly there almost as soon as you started throwing up, who held your head and brought you ginger ale and sat with you afterward, was Dad.
I sometimes think they would both have been happier if Mom could have become the Captain of Industry - or, better, a lawyer: she would have been formidable - and if Dad could have followed his gifts for nurture and for explanation into a public-school classroom rather than trying to make himself something he simply wasn't. But in the late '40s and '50s, that just wasn't the way the world worked.
On a few occasions over the decades, I've encountered people who thought less of my dad for being nurturing. A great many more people, however, have admitted to frank envy, and I'm pretty sure one or two of my clerical friends have invoked my description of my dad to illustrate a sermon on God the Father.
I think there's room for a fair bit of variation in what constitutes a family.