They'll look elsewhere

If you fill the heads of the ones closest to you with negativity, you don't have the right to be surprised at how it turns out.  One of two things will happen, and you may not like the road that is chosen.

If you are constantly pointing out everything that is wrong with a person, that person has a choice. 
They can seek out other people who agree with your assessment.  They'll live their whole lives believing the worst in themselves and not accept anything positive.  You'll watch them die a little bit inside every day until you get frustrated with their self-loathing.  Then you'll complain about that.  But you can't, really.  You did that to them.
or...
They will do everything they can to prove you wrong.  They'll throw themselves into every opportunity until they get back what you stole from them.  They'll stop at nothing until they find someone to tell them you were wrong.  And, you'll be able to do nothing but watch as they walk away.  You did that to yourself.

Relationships are fragile things - even the ones you think are cemented forever. 
Children grow up and away.  The further away they go, the better you'll know how you did as a parent.  If you want them to respect and love themselves, you have to show them that you respect and love them every day.  They're forming their view of themselves through your eyes.  But, there's always someone who will try to tell them about themselves.  Do you really want to put your child's self-worth in the hands of someone who has their own agenda?
Spouses who are used as doormats or punching bags will eventually make a choice too.  Stay in misery or step out into possibility.  Your actions make that decision easier for them.  If you don't want to wake up alone tomorrow - show them.  Otherwise, you don't get to be surprised when they find someone who gives them what you wouldn't.

The people closest to you will look to you first.  But, if they need to, they'll look elsewhere.