Is This A Male Thing Or Not?????

I have 2 sons aged 16 & 12 all I ask of them is to keep their own rooms clean and tidy,one doe's the dishes and the other hoovers,they have a dog that they promised if they got her they would take her out look after her clean up her toilet etc,they want for nothing they live in a nice home Im strict but fair with them and they know if they get punished they desreve to be,I have 2 jobs their dad died 6yrs ago and I have to be mum and dad which can be hard going at times...I find I'm having to continually repeat myself about the tasks they have if I ask them and it doesnt get done then I tell them and most of the time they suit theirselves and defy me Im at the end of my tether any suggestions please......