Siblings in an industrialized culture are encouraged to stay in contact and cooperate with their brothers and sisters, but its not mandatory. Older siblings in these cultures are sometimes given responsibilities to watch over a younger sibling every once in a while when the parents are out doing something. But in non-industrialized cultures being close to your sibling is necessary. These cultures also extend caregiving roles to older siblings, who are constantly expected to watch over younger siblings. So in less developed countries it is expected that the older siblings take care of the younger siblings and work together.