By definition they are all political offshoots of 19th century materialism.
For those who are not as well read (such as myself)on the 19th century roots of communism and fascism, would you please explain "materialism."
http://www.csustan.edu/History/Faculty/Weikart/hitler-evil.htm
http://en.wikipedia.org/wiki/Marxism#The_Hegelian_roots_of_Marxism (just to see what the commies say about themselves)
http://www.spectator.org/dsp_article.asp?art_id=6738
It's not so much being well read, but curiosity. Goldwater, peaked my curiosity, and probably said it best in The Conscience of the Conservative, in that Liberalism is the emphasis on providing the material needs of man (food water, clothing) where as Conservatism is the emphasis of the material needs of man (Freedom, opportunity, excellence ect). But the liberal association with materialism, and the unfortunate company they keep by that association runs much deeper.
Sorting out why materialism tends to end badly is an absolutely fascinating study, and is made difficult by the Marxist's talent for obfuscation (visually by creating straw men under the guise Dialectic Materialism, Capitalism IMO is one such straw men), and the fact that there is so little agreement between different branches of materialism..except for pointing fingers at each others mass murder.
Stranger yet, is how the occult and satanism tie in with Socialism and Nazism. Three groups we typically see as opposites or simply disassociated, but they all tend to end up falling into the trap of becoming their "own god". It's an inherent flaw, imo, of materialism.
The $1000 question is, how does liberalism stand for NOW while standing for Hugh Heffner, the party of Lewis Farakaun the party of a secular Jews, the domain of homosexual acceptance the domain of Margaret Sanger (who'd breed out ethinic minorities, Jews, homosexuals, and probably modern conservatives?