A TV remote control unit that does not work unless it detects a Y chromosome - using emerging 'Lab on a Chip' technology embedded in to the standard remote unit.

Two ways of getting the sample -

1. micro channels with the sampling liquid run across a special thumb pad on the side of the unit - sufficient DNA bearing material would be available from the normal shedding of the epithelial cells.

2. modified 'breathalyser' unit requiring the user to squeeze a little bit of spit into a small mouth piece connected to the DNA lab chip.

Note that this is not foolproof. An XX individual could possibly deceive the unit by using an XY cat or dog paw on the thumb reader, or could somehow (goodness knows how) obtain DNA-laden material from an XY resident in the house to spit into the sample tube.