They have observed correlation, but I don't think that warrants to interpret causality.
It could also be that freedom and democracy happen for some other reasons, and then later in a free and democratic society people will have less incentives to marry close relatives.
Comments
For starters:
http://jcc.sagepub.com/content/early/2012/04/24/002202211244...
They have observed correlation, but I don't think that warrants to interpret causality.
It could also be that freedom and democracy happen for some other reasons, and then later in a free and democratic society people will have less incentives to marry close relatives.
It's also important to note that the particular direction of the causality is not necessary for it to be an impediment.