I don’t think so—I read something about it being somewhat hard, but I don’t remember the details or the source.

Hmm, you got a point. The energy required to fly them should be spent while flying; if you’d do it on creation, there would be the risk of it being exhausted at some point. But Hogwarts has been running for centuries and it’s constantly doing stuff that needs lots more energy than a broom.

I guess my example is just silly. Without more information guessing about the relative magnitude of energy expended for various magics is useless.

I’d say that the energy involved for pretty much all spells is too huge to give any plausibility to the idea that it’s somehow generated by the human body through the genome, with or without a magic gene.