(e) persons of full age and capacity who are citizens of a country specified in the First Schedule: Provided that in prescribing the conditions and restrictions subject to which persons of any such country may be registered as citizens of India under this clause, the Central Government shall have due regard to the conditions subject to which citizens of India may, by law or practice of that country, become citizens of that country by registration. Explanation.- For the purposes of this sub- section, a person shall be deemed to be of Indian origin if he, or either of his parents, 4[ was born in undivided India.