mexican twins 

siblings that are born less than a year apart.

mexican twins is when one child is born and then 10 months later, or so, another child is born.

mexican twins by chicken jane September 24, 2013

Mexican Twin 

Half-brothers or half-sisters born less than nine months apart. Usually caused by a father having an affair while his wife is pregnant

Maria: My cousin and I spent the evening looking through face book at people with the same last names and we found out I had a Mexican Twin in Pico Rivera.

Mexican Twin by Dante84 May 15, 2015