The simian crease is one of the listed signs in Down Syndrome which would imply there's some genetic factor at play. My eldest daughter has a simian crease on one hand and the other hand is 'normal'.
Sovereign definition, a monarch; a king, queen, or other supreme ruler. See more.
crown (kraÊn) n. 1. any of various types of headgear, often made of precious metal and set with gems, worn by a monarch as a symbol of sovereignty. 2. the power or dominion of a sovereign. 3. (often cap.) the sovereign as head of the state, or the supreme governing power of a state under a monarchical government.