"I had to give back most of the cards, because her older brother was really close to my older brother," the singer tells PEOPLEJoe Jonas unveiling his 'Curated by' collection at Target SoHo in New York City on May 2.Credit: Jason Lowrie/BFA.comAccording to Jonas, he still has his Pokémon cards from when he was a kid. "I was able to find them again, and I still collect. I geek out on it," he tells PEOPLE. "I think it's definitely a new, but old, …