According to recent biological studies, if you analyse the blood of a Cantonese and a Hakka, you cannot distinguish them, because they share the same ancestry as late as in the late Ming Dynastry, even if you minus the factor of intermarriage. Even if he doesn't like it, he is always a Hakka in the eye of a Big-Hakkaist. Just tell Dr. Sun's granddaughter, Sun Ruifang, to give evidence to show that the Sun's Family is not a member of the Han-race, if she does not like to be Hakka. Unfortunately, our Hakka definition is only for our fun. Feeling and sentiment origin from contact and everyday practise.
Identity is a wonderful feeling.
You accept yourself because you are there. You cannot force someone, or someone cannot force you, to accept a new identity. Should we define Hakka just for our satisfaction, or also take care of what other people think and feel, this is the problem. What we need is an objective view. That is the point why I always stree on the practise language and culture, rahter than the historical ancestry.