Then form new nuclear families.

然后他们形成新的核心家庭。

But in nuclear families, fathers play this role.

而在小家庭里，父亲发挥了这个作用。

There are more and more nuclear families nowadays.

现在小家庭越来越多。

Nuclear families can have any number of children, own or adopted.

核心家庭中的子女，无论是亲生的还是收养的，在数量上并无限制。

There are often many nuclear families in one extended family.

在一个扩大的家庭中往往有多个核心家庭。