“Among the Hebrews, citizenship was derived by birth of Israelite parents”
“As, however, the arms of Rome extended her empire over the world, so did participation in her citizenship become an object of desire as a ground of honour, a source of protection, and a means of advancement.
“The right was variously acquired, by descent, merit, and manumission: — I. By birth from parents who were Roman citizens, thus in the Acts (xxii. 26), — ‘I was free bom;’ the rule being, that citizens beget citizens, but only in matrimonium justum, or where both parents were Romans”
http://books.google.com.ph/books?id=nxUBAAAAYAAJ&pg=PA372&dq=citizen+parents&hl=en&output=text#c_top
The People’s Dictionary of the Bible, 3rd Edition 1850
Chapter 2. Both parents citizens.