If they're all suddenly turning on you, I'd look at yourself and how you're interacting with them rather than the weather. Like a couple previous posters mentioned, pay attention to the snakes and their body language. Snakes can have off days too, and your siblings should be able to understand that if the snake isn't acting friendly, they shouldn't pick it up. That kind of basic knowledge of animal behavior will serve them well with any kind of animal - especially dogs, since dogs can do far more harm than a ball python.
I would relax and not worry so much about being bitten. It doesn't hurt that bad, you're not going to die, it's going to suprise you, but you and the snake will get over it and not be so frightened of each other.
The bottom line is that anything with a mouth can bite, and your family members should know this. Would you get rid of a chihuahua that snapped at people? Most people wouldn't... So why get rid of your snakes for being a little cranky?
Good luck!
~jenny
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"Polysyllabism in no way insures that what you're saying is actually worth being heard." - Blake (an e-friend of mine)
"I have never made but one prayer to god, a very short one: "O lord, make my enemies ridiculous." And he granted it." - Voltaire