If you are looking for a list of possible variables for bread mold:
Type of bread (wheat vs white, and even different brands)
Temperature bread is stored at
Open vs closed container for bread
Other food in contact with bread
Age of bread when purchased (fresh vs day old)
Preservatives vs no preservatives in bread
These are a few possible variables. You need to decide what you will test, and which of these you want to change versus which you want to keep constant. For instance: buy all of the same brand, but some wheat and some white. Keep some in the fridge in a sealed bag and some on the counter in a sealed bag. This should give you a few ideas of where to start with ideas about how you want to proceed.