How long have you had the kittens, the female may be feeling very insecure, so is weeing where your scent is strongest. Put an old unwashed jumper in their bed and make sure they have easy access to a litter tray at all times. It may be worth confining them to your lounge and kitchen where they will always be close to a litter tray.
Tidying up your clothes could help.
How old are the kittens? It would really help to know.
It may be worth taking them for a vet check to ensure that they have no probs, especially the one who wees. She may have a urinary problem. When you take her, you may as well take the other. Luckily the vet will only charge for one consultation and any meds you need.
Your vet will also advise you when to have them spayed. Best to have them done at five months.
More info about their general behaviour would help in solving this problem. For example, is the female particularly nervous?
