If you get defensive in a discussion, it’s because you think that what your counterpart is saying has at least some, and maybe a lot, of truth to it.
If you didn’t believe that the statement had any truth to it, you would either ignore it or laugh it off.
So you need to watch out for those statements that make you feel defensive. They are the same statements that you don’t want to be true, but at least to a certain extent are true.
The more defensive you get, the more truth the statement contains. And hence the more room for your personal growth if you are able to address the issue highlighted by the statement.