A common derailer that I have seen in many families is a lack of transparency. There is key information which is not being disclosed to other family members and, in some cases, to key people in a family business. Usually, this is caused by the holder of the information not trusting the other family members in some way. What is the cause? This is in part that person not trusting themselves and also having a desire for control and to manage outcomes. You will more often than not see this coming from the family leader who has a more naturally dominant behavioral style. You will also see this approach generally in at least one of the children. Interestingly, they expect transparency from everyone else.
Of course, there are times when it is appropriate not to disclose some sensitive information but you need to think very carefully about it. How will the other person feel?
The problem is that some of the other family members may either outright resent it when they find out. This will particularly be the case for those other family members who are very methodical and like plenty of information. Their tendency to trust is also lower. There will be others who will let it go for a few years, and then have a violent objection later when a problem emerges. Either way it does not build trust.
Whilst more open communication flows do create vulnerability which is difficult for some, it saves destructive behaviors later on which can rip a family and/or its business apart. Ultimately, this costs a lot more financially and non-financially.
One of the big points that I am bringing out in family meetings is to understand how to provide information to the different family members so there is trust. After all, trust is the currency of any family.