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.
suÂ·premÂ·aÂ·cy. n. pl. suÂ·premÂ·aÂ·cies. 1. The quality or condition of being supreme. 2. Supreme power or authority. (sÊËprÉmÉsÉª; sjÊ-).