Creating a Physics Asset

This is the default behavior of the physics asset that comes with UE4 after I press Simulate

Now, I want to create my own and to begin with I generate one automatically using capsules with sizes more than 20, thus generating the following

however when I press Simulate, the character falls into a messy position, I understand that this can be improved by tweaking the Contraints, but my question is the following, take a look at the following image:

Why do the capsules cross each other? Clearly the hand is going through the foot. This never happens with the default physics asset. What is the secret?