But the way I am reading this is different from some extended families where everyone seems to buy presents for the children. There is usually the idea here that once someone is an adult, they then participate as adults. It is a "family" thing, and does not imply the element of reciprocity between two parties. However, in this instance it is a group of friends who have opted to buy gifts for each other's children, rather than for each other. The reciprocity involved is between adults A and adults B, via gifts for their respective children. If adults A give gifts to children B, but adults B don't give any gifts at all, it becomes very one-sided. Keep in mind that these children were ONLY being gifted because of their relationship to the adults in the exchange, not due to any relationship to the gifter.