Poor? That is not right. A family that had no money couldn't afford such expensive clothes?
It's not true that we cannot tell how much money that had either. There are lots of clues in this painting. Look at their clothes and what is around them and try again.
The correct answer is that the family was wealthy. Only rich people could afford the luxury of having a portrait painted. There are also clues in the painting itself. Look at the mother's jewels, the expensive costumes and the land we can see in the background.