If you think that your estate plan just needs to address your assets, it's time to dig a bit deeper. To create an effective plan, you not only need to pass your assets on to your heirs, but you need to do it in a way that minimizes conflict. You want them to have strong family ties for the rest of their lives, after all, and you want to avoid litigation and estate disputes if possible.
One thing to bear in mind as you do this is the role of sibling rivalry. Many of those same conflicts that you saw when they were kids are just going to keep on impacting their relationships now that they are adults.
For instance, experts note that insecurity during childhood can last as children grow up. One child may feel like the "black sheep" of the family, thinking that you love them less than their siblings and that no one wants anything to do with them. If the estate plan is not perfectly equal and leaves them out in some fashion -- giving them less money or leaving sentimental items to other children -- then that insecurity may come flooding back. That could, in turn, lead to a dispute as they try to combat these feelings of insecurity and fight for what they want.
In other cases, rivalries revolve around children who are always trying to prove that they are better than their brothers and sisters. This can lead to long estate disputes as they try to get more of the estate than everyone else. They won't want to settle, even for a fair outcome, lest they feel like they "lost."
These are just two examples, but they show how important it is to consider family dynamics when drafting your estate plan.