Being brutally honest with myself

Most people are mostly honest. Some are very honest. There are those who just have a lot of trouble being honest.
Then there are those who are brutally honest. I am one of those people.
Recently I was chatting with a good friend of mine who told me that the reason that most really like me is because I'm genuine and very honest. Its also the reason that so many of my relationships end up blowing up.
Recently I did this, and it almost cost me a very good friend. I wish I hadn't done it in retrospect, but even so I'm pretty sure I will do it again.
Against my own interests, I seem compelled to say what I need to say, all the time knowing that its likely to cause a major hardship on the friendship. I have now done some soul searching to try and figure out why I do this, and in the process hope it helps others.
My father had his good points and deep down he was a very good person. Recently he passed away and I have done some thinking about some of the things he did and why I do some of the things I do.
The reason I probably do that is simple. I look a lot like him, and we have many similar traits. Some have said I'm a carbon copy of him. Mostly, that is true, for good or bad, it is what it is. I do have a lot of qualities that my mother did, in that I'm a very good friend and caring of others, but my main character traits come from my father.
One thing about my father that I chose not to be was dishonest and misleading. Throughout his life, my father just could not be truthful in many of the things he did, and as a result he had a hard life and so did my family because of it.
At one time it pretty much destroyed my mother and damaged my sister. I was the strong one and tried to be in the middle most of the time. I have never held a grudge against my father, and Ive come to think that he just couldn't help himself, it is and was a sickness that he could never overcome. But in my life, Ive always been very honest, brutally honest.
Its sad to me that me being the person I am often causes me to lose great friends. But as with my father, I really don't have any control over it.
In that respect, I'm just being brutally honest with myself.