Hi Monica. “They have two children” is correct, this is because a parent will always be a parent no matter how old children are. So for this reason the sentence “they have two children” is correct. You can explain further that the children are grown to give the person you are talking to a better idea of the children. So an alternative would be “they have two grown children” or “they have two children who are adults”. I hope this was helpful to many people😊

If you say "children were playing in the street", we are clearly talking about young people. If you say "that woman has two children" we are talking about a biological parent/child relationship and the children are still children of the parent even if the children are 80 years old and the parents are long dead. Perhaps to get away from the youthful aspect of the word "child", at a certain point, maybe when the children are around 20 or 25, parents tend to talk about their sons and daughters, rather than using the word "children". Even "grown children" sounds a bit like these adults are still children. Perhaps they are 30 years old and still living at home, for example. This is perhaps more information than you wanted to hear!

I would say 'They have two grown up children' if the children are adult and just 'They have two children' if they are indeed children/teens.

"Grown children" is the usual expression I have heard. But why worry about it? If someone who looks 30 says they have two children, most people would assume the children are not likely to be older than 10. If someone who looks 60 says they have two children, they are likely to be going to college.

Wikipedia profiles always say "children" no matter the age of the offspring.