Hello,
Please look at the sentence below:
‘’…He was born INTO a moderately prosperous family where his unmatched musical genius made itself known extremely early …’’
I think it should be :he was born IN…’’
Please explain it for me.
Hi Duc
Especially in combination with the word (or idea of) ‘family’, the usual preposition is ‘into’. You can find a lot of examples of ‘born into’ at the BNC website.
You would generally use ‘born in’ to talk about when or where you were born.
.
be born into/to/of something - be born in a particular situation, type of family etc
Can you explain more clearly about each collocation ?
into - expresses movement
in - expresses final position
“Born into” is the one you need, here.
Why? He was born into a prosperous family. He just had one family. No movement?
Think about expressions like:
brought into the family
entered into
And birth does involve movement, doesn’t it? 
But the passage here is about Mozart.
And? Even Wolfgang Amadeus was a new entry into the Mozart family, wasn’t he?
One-third of all children are born into single-parent families.
A doctor’s son, John Chisholm Winchester was born into a naval family on Jan 3, 1912.
Biscop Baducing was born into a noble family, then was ordained into the priesthood at the age of twenty-five.
Donald Dewar was born into a middle-class Glasgow household.
Dorena Knepper was born to be organized.
In both cases he is born of the cosmic Egg, but more important is the description given him.
The son of a farm labourer from Marton, James Cook was fortunate to be born into an age of great explorations.
This is Born to Burn Catering calling.
Just take it as a set phrase.