If I have the opportunity to decline the snacks as the FA is passing them out, I will. If I end up with an unopened/unwanted food item. I usually offer it to a seatmate.

If there are children seated around you, hang onto your pretzels etc. for a while and then when everyone else has eaten theirs, offer yours to the parent to give to the child. It will often help quiet the kids down for a bit.

I always offer it to the parents to offer it to the child. I never do it directly.