family is/are? (Singular or plural?)

The family _______ (is/are) cleaning the house.
Which answer is correct? Is or are?

In American English, family is always considered as a singular noun.
Therefore, the answer is 'The family is....'

HOWEVER;

For British English, 'family' can be a singular noun or a plural noun.
When you are referring 'family' as a single unit or think of them as a group, you use 'is'.
When you are referring 'family' to the individuals (family members), it's more common to use 'are'.

For example;
1) My family is big. It consists of 10 members. (singular)
2) My family are having lunch. They are having lunch at the restaurant. (plural)
*you cannot say 'It is having lunch at the restaurant' (singular)

Another example;
1) My family is big. (That means it consists of many family members.)
2) My family are big. (That means the family members are all fat/big.)

BACK TO THE QUESTION ABOVE, WHICH ANSWER IS CORRECT? IS OR ARE?