In 2014, Swiss photographers Stéphanie Borcard and Nicolas Métraux were in the Philippines documenting the stories of women trying to leave sex work when they learned about the children many call tisoy. Born to Filipina mothers, their fathers are foreigners, some of whom came to the Southeast Asian country as sex tourists and never returned again.

"The children face bullying at school and have to grow up without a father. Some idealise their paternal figure and start posting YouTube videos to find their dads. But usually, they do not have enough reliable information about their fathers to get in touch or find them," Borcard and Métraux told Refinery29 by email.

In the predominantly Catholic country, abortion is strictly illegal, contraception is expensive, and poverty drives many young women into sex work. In Angeles City, a red-light district full of brothels and bars caters to foreign tourists seeking a so-called "girlfriend experience" with young Filipina women. These paid sexual relationships can last for weeks or months.

"There is an enormous wealth gap between the sex tourists and the girls," Borcard and Métraux explained. Often, the men the photographers met said they were lonely; some even seemed in denial that their "girlfriend" was someone they were paying for sex.

"The problem is that most of these men are here for a set amount of time, usually months. All sorts of promises are made prior to their departure. The relationship often continues via social media until they come back," Borcard and Métraux added.

But for many men, when they hear about the pregnancy they are responsible for, "their reaction is, 'How do you know I'm the father?'" the photographers said.

If men consent to DNA testing and it confirms their paternity, they are responsible for monthly child support payments of about 10,000 Philippine pesos per month, or £145, until the child's 18th birthday, according to Borcard and Métraux. But many of the mothers they interviewed said the men refused to take responsibility, or stopped paying and disappeared.

Women are left to raise their children alone and children are left to wonder who their fathers are. Borcard and Métraux sought to capture these children's stories with a photo essay entitled Dad Is Gone. Ahead, they share their portraits with Refinery29.

Editor's note: All captions were provided by Borcard and Métraux and have been edited for clarity.