Background
When I first tried writing fantasy - a long long time ago - I wrote a book that was meant to be really serious and intense. However, I wrote it in a way where the characters joked around, and had more fun than they should have been having in a really dire situation. The whole thing turned into more of a comedic piece rather than being serious fantasy, and lost the atmosphere.
My new masterpiece trilogy is an epic. I've kept it super serious and to the point, and it's gone really really really really well. I'm infinitely happy. However, upon beginning book two, which I started 4 days ago, I have started slipping back into old habits. The characters keep making jokes, and generally enjoying themselves even despite the fact that their home has just been destroyed. I've gone through and edited some of the the humour out and have kept a bit more of the atmosphere of loss and mourning, but I came up with this question while doing it.
Question
Let's get right to it:
How much humour can you have before you lose the serious, intense atmosphere?
Is it right to include humour when something absolutely grievous is going on in the character's lives?
I feel as if I've got a good grip of it at the minute. I know what is silly and I should edit out, and what I should keep. However, this question does intrigue me!