Answer:
What is red and nailed to a wall?
I grow where no flower grows, where no light touches the walls, up or down, that I don't care, was here before people were.
I'm sometimes white and always wrong. I can break a heart and hurt the strong. I can build love or tear it down. I can make a smile or bring a frown.
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
What stays the same size no matter how much they weight?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?