The family in Islam is not restricted to immediate relatives of the nuclear family. Aunts, uncles, cousins, grandparents, second cousins, and even neighbors form a complex web of relationships that are tied together through mutual rights and responsibilities.
In Arabic, any adult woman can be called Auntie (Khala) and any adult male can be called Uncle (Amo). One's uncles are as close as one's father, and one's aunts are as close as one's mother. A cousin could be any number of relations: first cousin, second cousin, or a cousin related through marriage.
If something happens to a member of the family, the entire clan pitches in to offer assistance. If a woman is widowed, her father and brothers help her. If she has no immediate family, then uncles and cousins are obliged to pitch in. The elders are cared for by their children or by their nieces, nephews, or great-grandchildren. In this way, nobody is left to suffer in loneliness or poverty; there is always someone to look out for them.
While the culture of each individual family may vary, it is generally understood that one person's business is open to the entire group. It is not considered rude for a distant cousin to ask about a relative's income, or for a grandmother to ask about a new couple's plans to have children. The personal boundaries can sometimes be blurred because people consider “family business” to be everyone's concern. This is not done out of nosiness or to simply gossip. Within the family, there is generally a true desire to share, strengthen the bonds of trust, and offer sincere advice.