Great question and the last time I chose a seat on my transatlantic flight, I had an older gentleman ask to swap with his seat so he could sit next to his adult granddaughter. Ugh! I said yes because his was an aisle seat, but I liked the seat I selected better.

In today's air travel, if you pay extra for a seat of your choice, then there is no swapping with anybody. To that end, parents with children should choose their seats in advance instead of buying the cheapest fare and be expected to be seated next to each other.