Reproduction
Biological process by which new organisms are generated from one or more parent organisms
Is it true that gay male couples cannot naturally reproduce?
Gay men can have any of the various sex organs that humans have. Trans men will sometimes become pregnant with their significant other before transitioning medically. 
What defines a male gender? What organs are needed to impregnate someone? What organs are needed to carry a pregnancy? Does #1 exclude persons with either of #2 or #3?