President Vladimir Putin has two young sons with former Olympic gymnast Alina Kabaeva, both of which have been living in secret since their births, according to a report by a Russian investigative group started by a former billionaire Putin foe, though Putin and Kabaeva have denied romantic ties for more than a decade. Putin and Kabaeva share two sons, Ivan Putin and Vladimir Putin Jr., who were born in 2015 and 2019, respectively, according to the Dossier Center, a Russian investigative news organization that cited unnamed sources who claimed to regularly see the children. Putin, 71, has publicly acknowledged having...