When I print or "Print Booklet" in Adobe InDesign, I don't see any options about printing full duplex (both sides of the paper). I'm using a Mac with a Brother MFC-J6910DW printer. Does Adobe InDesign not support full duplex printing?
Duplex printing is a function of your printer and it's associated drivers and software. Indesign simply prints pages. It is the printer's job to duplex them if it has that capability.
The Brother MFC-J6910DW specifications do state it will duplex. You simply need to tick the option in the print dialog. THere should be an option for "2-Sided" or "Duplex" in the print dialog box provided you've got the drivers installed.