I am often asked at what age a child gets to decide where they want to live in a custody situation. It surprises many clients to learn that there is no definitive age when the child gets to "decide" in Missouri. In my experience, it seems that many people have a notion that 14 is the magic age, but I'm not sure where that comes from. It is true that the child's written consent is required for the child to be adopted in Missouri if the child is 14 or older and has sufficient mental capacity to give consent, but this rule has no application in the typical custody situation.
The custody statute that the court is required to follow in custody matters (and which in turn guides us in settling cases) does require the court to consider the "wishes of a child as to the child's custodian", but it is only one of at least eight factors the court is required to consider. Further, the court is not required to consider the wishes of the child at all unless the child is of sufficient age to form and articulate intelligent reasons for their preference. Generally, the older the child, the more weight is given to the child's wishes. However, we can all think of reasons why the child wants to live with one parent over the other for reasons that have nothing to do with the child's best interests. "Dad said he'd buy me a car if I move in with him" is a classic example.
The advice I give to clients about how much weight will be given to the child's wishes necessarily changes based on the child's age. If a client tells me that their four year-old always says he wants to live with him or her, it is a red flag to me that the client may be having inappropriate conversations with the child. Suffice it to say, a four year-old's articulations about who they want to live with are not going to be given much, if any, weight and may backfire on the parent trying to use them in a custody case. If the child is sixteen and can articulate mature reasons for why they want to live with one parent over the other, I typically advise clients that the child's wishes will be given a lot of weight, but the overall merits of the case will obviously depend on the circumstances.
If you are in the unfortunate position of having to ask the court to make a custody decision and you and your attorney decide that the child's wishes need to be presented, it should be up to your attorney how that happens. The attorney will need to decide the best way to get that information before the court. It may be through a Guardian Ad Litem (an attorney appointed to represent the child's best interests); it may be with an "in camera" (in the judge's chambers) interview with the child; it may be with some other evidence that will have to be carefully presented so it does not constitute hearsay; or it may be with the child's own testimony in open court. These decisions need to be considered very carefully by an experienced attorney, particularly as to when (if ever) to call the child into court. Clients often wish to have the child "tell the judge where they want to live", but placing the child in the middle in this way is to be avoided.