What is the most unfair advantage a person can have?

Not needing a lot of sleep.

This is a genuine, and unfair advantage, since it is almost entirely genetic, and not based around lifestyle or nutrition. Some people (Margaret Thatcher, Napoleon, etc) were able to function very effectively on just 4 hours of sleep, leaving them 20 hours in the day to be productive. Others need 8 hours just to feel normal, and that is 4 hours that they fall behind every single day, with no way of changing that.

It’s easy nowadays to use all sorts of efficiency methods and systems to help you get more done in the day, but as you push this further you inevitably hit a limit where you are as productive as you can possibly be. Unnecessary work is delegated out to either people or technology, and you are left doing just that which requires your personal input. It’s at that point that the extra 4 hours become a fundamental unfair advantage.

Link on Quora

What is the most unfair advantage a person can have?

Emotional detachment.

The power to ‘feel’ less. As an emotionally detached person, you are less prone to getting impacted by others. That would entail lesser heartbreaks, lesser disappointments and lesser number of people weighing you down. You have great control over situations that could trigger anxiety or depression. You can always concentrate on your goals and ambitions without any kind of emotional baggage holding you back. You always tend to have a very practical and meaningful approach towards things and you always view them in an unbiased light. As a result, you are less susceptible to wrong decisions. 

Personally, I would kill for something like this.