How To Treat Shaky Hands?

My son aged 26, height 5'8", weight 50kg, BMI 16.5 shakes his hand while lifting tea cups or any other small objects. He do not have habits of drinking alcohol or smoking even occationally. Shaking in hands seems heridetary in our family as some of my brothers and cousines has this problem, but it never hinder their health otherwise. But my son missed a wedding alliance as bides party has find the hand shake and cancelled the alliance at the last moment. Please let me know whether there is remedy to rectify this problem and to improve his weight. Even though he eats well he could not improve his weight more than 55kg. He plays carroms and as a software engineer, he does his computer work with out any hinderence and no other compliants, except occational claim of gas in the stomach.