Here's a simple way of how the GM's find out.

You pwned some noob ganker, and he reports you for botting because they don't understand how you can control 5 toons at once.
or
You are going through Iron Forge and people report you for botting because they don't understand how you can control 5 toons at once.

GM checks out your account, the names are not the same, must not be the same owner.

Banned.

The End.

Moral, spend the little bit of money now to have your own accounts at the beginning, or spend the little bit of money and a whole lot of time doing it all over again because it wasn't your account.