I do think you have to "accept" some traits in your dog sometimes and acknowledge they have an issue you may always have to watch for.

Even with Oscar already i know he has a "snappy" disposition and has some possession guarding insticts, it is a work in progress that i am always bang ontop of but i have learnt (and am teaching the children) to read the signs (like DT said) and minimise the risk. I think he will always have the potential under the wrong circumstances bit then you can own a dog for 10 years and one day it decides it hates the postman