President Donald Trump set off another round of speculation about his mental health by mixing up his father's birthplace.The 79-year-old president hosted German Chancellor Friedrich Merz on Tuesday at the White House, where he took questions about the U.S. attack on Iran and seemingly mixed up his U.S.-born father, who died in 1999, with his German-born grandfather, who died decades before Trump's birth."My father was born -- he knows all about my father -- my father was born there," Trump said....