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'.
A unilateral single palmar crease was also reported in a case of chromosome 9 mutation causing Nevoid basal cell carcinoma syndrome and Robinow syndrome. It is also sometimes found on the hand of the affected side of patients with Poland Syndrome and craniosynostosis.