At what age can your child make the decision to live with you in Missouri?
ANSWER: Never. Not until age 18. One of the factors the court will consider is the wishes of the child as to what parent he wants to live with. But there are a lot of other factors the court will consider, so the wishes of a 10-year-old typically don't mean squat. Keep in mind, however, if there is evidence of abuse or neglect of the child, an attorney will be appointed for the child (called a guardian ad litem) and he will speak to the child and represent his interests in court.
As the child gets older, the court will take his opinion more seriously. As the child gets older, the court will, in general, give more weight to the child's opinion. But, the court knows most kids don't know what is in their best interest. Billy may want to live at dad's house because there is no discipline and he can pretty much do what he wants. That is not going to fly with any judge.
A kid with a driver license and a vehicle has a much better chance of living with whatever parent he wishes. I've had several judges tell me if the kid can drive, he's going to live with whatever parent he wants because the court doesn't want to have to involve the juvenile authorities. Of course, there are always exceptions, but that is a general rule.