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.
Definition of monarch. 1 : a person who reigns over a kingdom or empire: such asa : a sovereign rulerb : a constitutional (see 1constitutional 3) king or queen. 2 : one that holds preeminent position or power cotton, monarch of the textile world â Wall Street Journal.