1 The processing time does not apply to services where prior approval has to be obtained from authorities in India or elsewhere. For such cases, the processing time is a minimum of thirty (30) business days.  The Consular Officer can at any time call an applicant for a personal interview.
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'.
simian crease. Simian fold Neonatology A dermatoglyphic pattern of a single deep transpalmar crease formed by fusion of proximal and distal palmar creases, classically seen in trisomy 21, but also in trisomies 13 and 9, fetal trimethadione syndrome. See Dermatoglyphics. Cf Triradius.