Were they literally the sons of Yonadav ben Rechev?
Radak: "Avinu" means our ancestor. We find Yonadav ben Rechev at the time that Yehu ruled, almost 300 years ago!
Why did he command them not to drink wine?
Radak: It is known that one who errs with it (drinks too much) goes crazy - "v'Chol Shogeh Bo Lo Yechkam", "l'Mi Avoy l'Mi Midyanim l'Mi Si'ach l'Mi Petza'im Chinam l'Mi Chachlilus Einayim; la'Me'acherim Al ha'Yayin" (Mishlei 20:1, 23:29-30). The reason why the 10 tribes were exiled was due to drinking much wine - "Hoy Ateres Ge'us Shikurei Efrayim", "Hoy Giborim Lishtos Yayin", "Hoy Mashkimei ha'Boker Shechar Yirdofu" (Yeshayah 28:1, 5:22, 11). Also Yehudah and Binyamin were exiled was to wine - "v'Gam Elu b'Yayin Shagu" (ibid., 28:7). The first one who drank wine, even though he was a Tzadik and Tamim 1 , he became drunk and was disgraced.
I.e. Noach (Bereishis 6:9). He is the first one whom the Torah says that he drank wine. (PF)
