Hmmm.... I’d be careful trying to compare these people to what we consider the modern nuclear family.
As was the case throughout most of human history, they probably lived in a multi-generational family setting, with three or more generations (including widowed aunts, bachelor uncles and infirm grandparents) living close by.
The post WWII nuclear family of mom, dad and the kids is a historical anomaly.
The article said testing done on the remains indicate they were related as mother, father, and sons. But the article did agree with your assertion that we mustn’t assume this was the norm.
The fact that these people were buried together like this suggests that this culture consciously separated the nuclear family from the rest of the group. Pretty neat but I would guess nuclear families as the human norm are at least 10,000 years old.