@igm,
I agree; humans never have 'FULL KNOWLEDGE' in anything we do, and we must label them 'guesses.' I believe that the fact that we do make important decisions such as to marry and/or to have children are often thought out more than going to the grocery store to buy junk food we pick off the shelves as we walk by.
We also try to create healthy habits with eating more veggies and fruits, and try to exercise more often, but fail to do so. In other words, we think more about that subject, but it doesn't necessarily mean we follow what's good for us.