If you have minor children your estate plan should include financial provisions for them and the designation of both a trustee (someone who will manage your assets and a guardian (someone who will be responsible for the upbringing of your children.
If you have children who are 18 years or older, they need a plan to protect them from a disability or period wherein they have become incapacitated. It is a mistaken belief that you as the parent can make medical decisions for your child once they are emancipated. Proper planning can help you avoid this pitfall.