The US, which imposed sanctions on Russian President Vladimir Putin's daughters, identified them as Katerina Tikhonova and Maria Vorontsova. Vorontsova, Putin and his then-wife Lyudmila Shkrebneva's elder daughter, is a paediatric endocrinologist, specialising in genetics and dwarfism, The Independent reported. Katerina, their second-born, is an academic and an ex-acrobatic rock 'n' roll dancer.