Dads is a new book coming out at the end of this month that focuses on gay fathers and their families. It’s the work of Belgian-born, New York-based photographer Bart Heynen.For Heynen, who received a Master of Arts degree at the Vrije Universiteit Brussel and studied photography at the International Center of Photography in New York City, the subject matter is close to home: he lives in NYC with his husband, Rob Heyvaert, and their 10-year-old twin boys.The two men met when they shared an elevator ride in their building in Antwerp and have been together 25 years.