(1) A person is capable of having an independent domicile if:
(a) he has attained the age of 18 years; or
(b) he is or has at any time been married,
and not otherwise.
(2) Subsection (1) does not apply to a person who, under the rules of law relating to domicile, is incapable of acquiring a domicile by reason of mental incapacity.