Hrithik Roshan has two Thumbs in Right Hand. It is supposed to bring good luck when you have two thumbs in Right Hand.

The world record holder for highest number of digits is Akshat Saxena from Uttar Pradesh, India. He was born in 2010 with 7 digits on each hand and 10 digits on each foot, for a total of 34 digits.

Radial or preaxial polydactyly is refers to the presence of an extra digit (or extra digits) on the radial side(thumb side) of the hand. It is most frequent in Indian populations and it is the second most common congenital hand disorder. The incidence of radial polydactyly is reported as 1 in every 3,000 live births.

source: http://en.wikipedia.org/wiki/Polydactyly