My parents are against my double first-cousin marriage

The Express Tribune, a major daily English-language newspaper based in Pakistan, has an advice column called "Ask Asad".  A man wrote in asking whether he should marry his double first cousin.  On average first cousins share about 12.5% of their DNA, so double cousins share 25%.  This is equivalent to half-siblings or an uncle or aunt.

I am in love with my cousin and want to marry her. She loves me too and wants the same, but our families are against it because she is my double first-cousin.

Her mother is my father’s sister and her father is my mother’s brother. My family really likes my cousin but when they got to know that we are in love with each other, life has been tough for us and especially for her.