Special relativity predicts that either twin ages more slowly than the other, as judged from the other twin's system:
http://www.people.fas.harvard.edu/~djmorin/chap11.pdf
David Morin, Introduction to Classical Mechanics With Problems and Solutions, Chapter 11, p. 14: "Twin A stays on the earth, while twin B flies quickly to a distant star and back. [...] For the entire outward and return parts of the trip, B does observe A's clock running slow, but enough strangeness occurs during the turning-around period to make A end up older."
Special relativity's prediction that either twin ages more slowly than the other (as judged from the other twin's system) leads to absurdity unless "enough strangeness occurs during the turning-around period to make A end up older". However, during the turning-around period, the traveling twin is very far away from his stationary brother so the idea that "enough strangeness" is somehow produced during the turning-around period and this "enough strangeness" miraculously affects the distant stationary twin is simply idiotic.
Pentcho Valev