Nobody likes to think about their own mortality, but while it may be okay to throw caution to the wind when you are single (or even when you are a part of a couple), once you become a parent, there is more at stake than who gets your stuff. Your children will need to be financially provided for by you or someone else. You will need to decide who that person is, and legally nominate them. If you do not, your child may go to someone you do not want as their legal guardian, or worse, become a ward of the state.
If you do not have a will, your estate will be divided up according to the decision of the courts. While this is a standard formula, there is no guarantee that the people you want to have your worldly belongings will be the ones who get them. There is also no guarantee that your children will be properly cared for.
If you have a will, however, you decide who gets what, who acts as an executor or trustee while your children are young and they will be legally accountable to ensure that your wishes are carried out.
A good idea, while it can be more costly and more time consuming, is to have a separate will drawn up from your partner. That is because if you do not, the surviving partner is legally bound to the document you have created jointly. If their circumstances, and those of your children, change dramatically after you pass away, it may be difficult or even impossible for them to change the document you co-signed.
