Please help me identified my cat's breed?

by Zul
(Singapore)

I've two cat, been having them since they were kittens. Now already almost 4yrs & still yet not sure what breed of my cats. How I got them? A mother cat came to our house and give birth to them, after she raise them till no longer need to be feed milk, she left them. That when we took over & take care of them. We look for her mom, but unable to locate her till I got a shocking news from my sister that she have been attack & bitten to death by a dog. Anyway, hope anyone here can help to identified what breeds of my cats, thanks.