Can child decide when to live with other parent?

My son is only 3 1/2 yrs old and I just received an email from my ex stating:
“because when he turns 12 he will be able to decide for his self, and you should know he is gonna want to come live with me, and i cant blame him.”

  1. If my ex wanted his son to live with him wouldn’t he need to file for custody?

  2. Wouldn’t my ex need to show reasons why it is not in the child’s best interest for him to stay living with me?

  3. Would a judge just uproot a stable living condition and agree that the child can live with his father? His father lives in a different county, which means new schools, new after school activities, friends, etc.

  4. Is there an age when the child can decide? If child does decide, what steps need to be taken?

My ex has no reason to think that his son isn’t being properly cared for in my care, he is just spiteful and mean.

THANKS FOR CLARIFICATION!!!

Yes, if your ex wishes to assume sole physical custody of the child, and you do not agree, he would have to pursue and action in the court system and prove that the child’s best interests would be met by living with him.

The court considers all factors relevant to what is in the child’s best interests in making a custody determination, including who is and has been the primary caregiver.

There is no age when a minor child can decide which parent to live with, though a judge may agree to hear from the child, a child’s wishes are not determinative.