Re: Shouldn't identical twins have approx. the same amount of hair?

Frustration of the unknown - a hallmark of science.

First of all, identical twins are only genetically identical - all the tiny 
differences that occur in a life make subtle differences crop up. What you 
describe is vexing - far beyond the usual differences that crop up between 
twins.

A corellary question, is it possible they are fraternal twins, and just 
look a great deal alike? This is probably a dumb question, but I was just 
wondering.

Second, as you probably know, alopecia is an autoimmune disease, where the 
immune system attacks the hair folicle/or hormones which trigger hair 
production - and the hair of the sufferer falls out.

I would guess that twins should have the same amount of hair, unless one 
has an infection or was exposed to something (many autoimmune disease have 
environmental triggers.)

I am not a medical doctor, and can't honestly offer you any medical advice.

There is the ubiquitous webMD, and here are a few web sites:
 http://www.alopeciaareata.com/ http://npntserver.mcg.edu/html/alopecia/AlopeciaFAQ%28part01%29.html http://www.follicle.com/

I can vouch for none of them - 

Finally, from personal experience, I know a family where two of four 
daughters suffered from alopecia in their pre teens, but the condition 
cleared up by the time they were 14 or so. It's a strange malady.

Good luck, and ask your doctor lots of questions - you deserve all the 
answers you desire!

Regards
Tod Companion, Ph.D.