How to tell which nationality I look like?

This isn't one of those ' do I look korean ' questions. I'm a 13 yr old girl, I am born and live in Singapore. So I guess I'm Singaporean, and my ancestors are from China. But sometimes I doubt it. My cousin is half Singaporean and half Australian cause their dad is Singaporean and their mum is Australian. Many people say that I look like my cousin. Is there a way to tell Chinese, Korean or Japanese and other Asians apart? By their facial characteristics, eyes and nose? Thanks.