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.
monâ¢arâ¢chy. 1. a government or state in which the supreme power is actually or nominally lodged in a monarch. 2. supreme power or sovereignty held by a single person. 3. the fact or state of being a monarchy.