I consider both myself and my husband third culture kids, at least to some extent. We have enough of a US background to be heavily influenced by that (I would say it is our dominant culture), but we also have enough of a Hispanic background to keep us from fitting in completely. Everything from greetings, to personal space, to food and social choices, to language, to parenting practices are affected. I didn't realize how out of mainstream beliefs I was, though, until we became parents.
My Hispanic friends don't ask a lot about whether the baby is sleeping through the night. Most of them expect her to sleep with us. Many of them, especially those from rural areas, find nothing unusual about child led weaning. One even shared that his uncle nursed past ten! He says that he is grown now, a kind man, and extremely healthy and strong. He attributed it to the extended nursing. My father in law breastfed until he was seven, and that was a good thing. They love the idea of baby wearing, and talk about how their abuelas used to wear their babies.
Also, in a way that is hard to define, they are welcoming of children. We don't even have an exact word in Spanish for babysitter, although we use niñera. It is generally expected that the family will go places together, and if parents are welcome, then so are babies. As in nearly every country other than the US, most boys are left intact. Non-allopathic health care is respected. And although corporal punishment is still the norm in much of the Spanish-speaking world, in Spain, Costa Rica, Venezuela and Uruguay, all corporal punishment is illegal.
However, we do not pierce our daughters' ears as babies. Nor do we shave their heads so that their hair will grow in thicker. We also have boundaries as to how other adults, even relatives, correct our children. We don't try to shame them or make up things that other people may be thinking about them to manipulate them.
Obviously, any time you make generalizations about cultures, it is a little tricky. The accuracy will always be limited. Among Hispanics, particularly those in urban areas, things are becoming much more like mainstream US views. Yet it is comforting for me to know that in some places, I am nor weird. :D
I would love to hear from other moms with a foot in different cultures what things make you feel that you fit in, and which ones don't. Please share in the comments. :)