Does stress, diet and smoking have a key role in male balding?

Today we continue the third of our week long look at male balding. I am often asked how much of a role does diet, stress and the environment have in male balding?

We currently believe that factors such as smoking, alcohol, stress, and sun exposure and obesity do have role in accelerating hair loss but the key question is "how much" of a role do they have? To look at this question in more detail, we need to look back at some brilliant studies of identical twins.

Identical twins carry the same genetic profile. By studying the appearance of identical twins at various points throughout their lives, we can get a sense of how important factors like genetics and the environment actually are. If genes are the key important factor in balding progress then, identical twins should look ‘identical’ in terms of their hair density. In contrast, if environmental factors like smoking, stress and ultraviolet radiation are important, identical twins might not have the same hair density because their environment is different. 

The Hayakawa Study 1992

Studies in 1992 revealed that genetics is by far the most important factor and the environment only has a minor role. 92 % of identical twins have "no significant" differences in their hair density. 8% of identical twins have a slight difference. Interestingly , no twin had a striking difference!
There studies support the notion that one’s genetics is by far the most important factor in the balding process. 

Is there any role for 'non genetic' factors?

That answer is certainly yes, but at least in men it appears much more minor in terms of the magnitude of involvement in the balding process. Other studies have suggested that "epigenetic" factors like stress, smoking and diet and sun exposure do have a role - but it is likely a minor role.

Reference

Hayakawa K, et al. Intrapair differences of physical aging and longevity in identical twins. Acta Genet Med Gemellol (Roma). 1992.