Note on the free will vs. brainwashing argument.
There has been some controversy over the years about 'cults' and 'brainwashing' (aka 'mind control') . Some believe that individuals should be legally protected against brainwashing by predatory cults, while others believe that brainwashing is a myth, and that any attempt to regulate religious movements would be an infringement of civil and religious liberty.
The concept of brainwashing is especially contentious. As one legal commentator put it:
' ... Americans have a fundamental belief in free will. To those with that belief, brainwashing is especially terrifying, because it involves the loss of the core of individual liberty.' 
However, this fear may be misplaced. Brainwashing does not involve the loss of the core of individual liberty. It does not involve the loss of free will. Brainwashing does not directly control or negate a person's free will, but rather it strongly influences the basis from which a person forms their will. After brainwashing, free will itself remains intact, but its basis has changed.
It is a person's belief system and worldview which largely determine a person's free will. A person's belief system is the basis from which they make their choices and decisions. If you can influence and change a person's beliefs and worldview, then you can change a person's will, and therefore those aspects of their behaviour which are subject to free will.
In other words, free will is not an absolute, but is somewhat dependent on causes outside of itself. Below are some quotes in support of this argument:
'In human freedom in the philosophical sense I am definitely a disbeliever. Everyone acts not only under external compulsion but also in accordance with inner necessity. Schopenhauer's saying, that "a man can do as he will, but not will as he will" has been an inspiration to me since my youth up...' 
Thomas Hobbes wrote:
'Nothing takes a beginning from itself, but from the action of some other immediate agent, without itself. Therefore, when first a man has an appetite or will to something, to which immediately before he had no appetite nor will; the cause of his will is not the will itself, but something else not in his own disposing. So that, whereas it is out of controversy that, of voluntary actions the will is the necessary cause, and by this which is said, the will is also necessarily caused by other things, whereof it disposes not, it follows that voluntary actions have all of them necessary causes, and therefore are necessitated.' 
'The will cannot be called a free cause, but can only be called necessary. For the will, like all other things, needs a cause by which it may be determined to [existence and] action in a certain manner.' 
(Of course, there are other opinions on the nature and origin of human free will. In the opposite camp to Einstein, Schopenhauer et al is for example: 'Over himself, over his own body and mind, the individual is sovereign.' - J.S. Mill, On Liberty, 1859)
In general, a person's belief system and worldview (and therefore their free will and the choices they make) can be and are influenced to varying degrees by various sources: their parents, friends, schoolteachers, the media, etc. This is how culture evolves and perpetuates itself. For the most part, at least within a democratic, open society, these influences are established, widely known about, and subject to review and regulation, through the law and through other less formal social processes.
Cults, on the other hand, are able to influence a person's beliefs and worldview (and the choices they make) through processes which are not widely known about (and not yet recognised in law); which are often damaging to the individual and ultimately to society; and which are not subject to review or regulation by any agency independent of the cult.
Cult belief systems differ from 'mainstream' belief systems in significant ways. For an outline of the nature of a cult belief system, and how it can gain hold of a person's mind, see the essay: 'Mind Control in 20 minutes'
 Marci Hamilton (Paul R. Verkuil Chair in Public Law at Benjamin N. Cardozo School of Law, Yeshiva University, New York), in her article: 'The Elizabeth Smart Case: Why We Need Specific Laws Against Brainwashing'
 From p.2 of Albert Einstein's Autobiography "The World As I See It" translated by Alan Harris pub Bodley Head 1935 ISBN 0-8065-0711-X
 From p.76 of Schopenhauer's 'On the Freedom of the Will' translated by Konstantin Kolenda pub Basil Blackwell, quoting from Thomas Hobbes 'Of Liberty and Necessity' The English Works of Thomas Hobbes - London 1840.
 From the same Schopenhauer book.