Are you talking about developing DID or a Dissociative Disorder? There is a difference.

People develop dissociation as adults, but Tollhouse is right. There is, according to the experts, no adult onset of DID.

And the majority of those experts believe DID usually happens to children around the (average) age of six years old and under.

There are also other disorders that include dissociation if DID doesn't fit. What does your T say about it?