Alexander I Pavlovich Romanov

Alexander I Pavlovich was born on December 23rd, 1777.  Alexander I Pavlovich's father was Paul I Petrovich Romanov and his mother was Maria Sophie Feodorovna von Wurttemberg.  His paternal grandparents were Peter III Romanov and Catherine II von Anholt-Zerbst. He had three brothers and six sisters, named Konstantin Pavlovich, Nikolai I Pavlovich, Michael Pavlovich, Alexandra Pavlovna, Helene Pavlovna, Marie Pavlovna, Catherine Pavlovna, Olga Pavlovna and Anna Pavlovna.  He was the oldest of the ten children. He had a half-sibling of unknown gender named ?.