One of the decedents was Xerox LOOPS, which was an Interlisp OO extension and ran on their Alto and Star systems (IIRC). I had the opportunity to play around on one of these and hacked some LOOPS code back in the day. LOOPS itself had a very interesting mix of OO and 'data' oriented programming. It introduced the idea of 'composite' objects - a language formalism that allowed for the instantiation of groups of objects based on a template, among other novel language features.
http://www.markstefik.com/wp-content/uploads/2011/04/1982-Bo...