Brother could have just forgotten like a normal human, doesn't make him stupid.

Not forgotten for two weeks

but who doesn't use the oven for two weeks?

In OP's defense, we don't cook with the oven very much in the summer either. It makes the house too hot. I haven't looked in my oven for at least a week or two, if not longer.

Stove > Oven, pop open a can of soup or throw on a few eggs!

I was thinking the same thing! Even here in the south I cook in the oven 3+ days a week during the summer. Cookies, cakes, dinner, and a host of other odds and ends stuff

We hardly ever cook in the oven, mainly on the cooker

It gets so hot in the summer with the oven on, we BBQ most of our meals so I can go a long while without looking in the oven as well.

we don't much use for our oven.

Ovens are somewhat air tight. They have to be, or they wouldn't serve their purpose. Add tinfoil on top and it wouldn't have been too hard for it to go unnoticed, especially if they don't cook very often.