Clue 2
What restriction could there be on the number of the house next door? The only thing that seems to make sense in the context of this problem is that it must be even. But why would that be?

Clue 3
I imagine this is meant to preclude a possibility which has a much older child (36 years?) as the oldest. But I know someone aged 50 who is learning the piano!

This question is for testing whether you are a human visitor and to prevent automated spam submissions.