Hi Richard, I just commented on your writing before I saw this question. ลูกครึ่ง is a very common descriptor when each of your parents is of different nationality/ethnicity. ผมเป็นลูกครึ่งไทยฟิลิปปินส์ (I am half Thai and half Filipino.)

You could say, "I come from many backgrounds", or "My heritage is very diverse!" :) I am a teacher on Skype, please make a lesson for more answers!