Andy Pettitte

Does a good fastball run in Pettitte blood? Derek Jeter is certainly hoping so ... 'cause the Marlins exec said he signed Andy Pettitte's son this week because he's banking on the kid's DNA!! Jeets spoke about the Marlins' deal with Jared Pettitte out in NYC to Adam Glyn ... explaining, with a…

Ex-NY Yankees pitcher Andy Pettitte has found his second calling -- he's a football coach ... even though he says he doesn't know a helluva lot about the sport. 42-year-old Pettitte retired back in 2013 after 18 seasons in the league ... but Andy tells us he's been keeping busy spending time with…