[mesmark]

'How many people do you have in your family?'

Is this a general construction you would use?

The answer then being:

'I have four people in my family, my parents, my sister and me.'

It's strange to me. I'd say 'How many people are there in your family?' If I would actually ask a question like that at all

Since it is a common question in the local L1 they like to ask it in English. I was approached about it as a teacher was going to put it in a test and we started to discuss it. Turns out, this exact example is in the workbook that accompanies the textbook. So, I lean toward the side that this must be some other English, but it could be 'Japanese English.'

I said that we generally only use 'have' when we are in a position of power over the group.

I have 3 kids.
I have 15 people working for me. (I'm the boss)
My company has 120 employees. (It's my company.)
I have 32 students in my class. (I'm the teacher.)

but if I'm a student for example, I wouldn't say:
'I have 32 students in my class.'