I just wanted to add that although most of what Zig said is somewhat true, I don't think it's fair to say that 100% of the time it's true that mixed race children are a product of some kind of white male fantasy Thai women have or some Asian fetish the white parent has. I'm Thai and I grew up in international schools, so a lot of people I know are mixed race and their parents are happily married. I'm not saying it doesn't happen because yes, it does, and it's a massive problem. The fetishisation of Thai women is a huge obstacle that many Thai women face both in Thailand and outside of it. But I don't want there to be misinformation as well that all mixed-race Thai kids come from that kind of background. It's not true. Like I said, most of my mixed race Thai friends have happily married parents. My aunt married a Swiss man and they're happily married as well.
Thai beauty standards are like most Asian industries. They want super thin and pale skin. Actually, growing up, I feel like most people preferred Thai women (and men) who were of Chinese descent rather than those who were 'pure' Thai. I think it's because 'pure' Thai people are more inclined towards being darker skinned. I'm fairly pale, but I tan super easily and I can get really dark if I'm in the sun long enough. Most of my family are like that, but the ones that live in Bangkok are paler than my relatives who live up north. And there is definitely prejudice there because darker skinned people are stereotyped as being of a lower socioeconomic class. Thai culture is VERY classist. The divide between the rich and the poor in Thailand is so ridiculously large, they might as well be on different planets.
Most Thai actors/actresses come from affluent families/backgrounds. There are hardly any rags-to-riches stories because of this, and that's why there's a tendency for the entertainment industry to big up that background, like whether they studied abroad or attended international schools and which school, etc.
I'm just saying... For those non-Thais, don't look at our culture in such a black and white paradigm. There are a lot of exceptions, factors, and nuances that you'll miss otherwise.