The US is very strange when it comes to forcing people to work or lose their jobs in the event of a family member's illness or birth (or your own illness, but not birth). It's pretty much restricted to: your parents or your child, or spouse but rarely to the sibling because I guess your sibling's parent/child/spouse has to take care of them? That's not super realistic I guess but I suppose that has more to do with legal/financial relationships than anything.