Now, either we're all just becoming really grumpy as we get older, or it may mean that as you understand laughter better, and you are getting better at doing that, you need more than just hearing people laugh to want to laugh.
Soit nous devenons tous grognons en vieillissant, ou nous comprenons mieux le rire, nous nous améliorons et il faut plus qu'entendre un rire pour vouloir rire.