People who are incredibly charismatic have personal power. That is, their life is so together that they are able to do whatever they want. I must say that charm is different from charisma. A guy/girl may be charming and that to me refers to the fact that they could be charismatic if they had their life together.
What I mean by personal power is that the choices we make. I think that charisma is something that anyone can develop.
Having grown up without much in the way of positive male role models, and now dealing with my own beta nature (with infrequent episodes of behaving as one of these alphas everyone is talking about), I've found that a good deal of my problems with other people come from my own weakness. I have had relationships with some very strong women and I've been unable to provide them with the strength or reliability they crave.
Using letters to describe people is no different from using words like "dominant" "funny" or "pretentious"; they're all just symbols. Except using letters might be more accurate because the letter is openly ambiguous whereas a word tends to over-specify and not encourage one to look further into its meaning. I think, Louise, that you should get over your fear of using letters lest it prevent you from learning anything here. There are different roles that people can take, certain stable niches that we can fall into that society (that is, we) creates for us.
Alpha, beta, delta, I don't know exactly what they mean, but I know that our behavior in terms of possessing personal power and the way we use it, can greatly determine our happiness. It is in our best interests to understand that, not to believe that somehow by using greek letters we are locking people into developmental traps. Understand these terms, study what they mean, and if you can do anything to help your sons be happy, do it, even if it includes teaching them to harness the power to be Alpha. This isn't Brave New World, no one is dousing fetuses with alcohol to stunt their growth.