jlinger thank you very much for your quick reply.
so "born to the son of.." means "he is the grandson of.." I really didn't know that, I thought it meant "he is the son of.."
These two sentences are original:
"Explorer, navigator, Columbus was born in 1451, in the Republic of Genoa
to the son of a weaver."
"Columbus was born in the Italian port city of Genoa,
the son of Domenico Colombo, a weaver, and Suzanna Fontanarossa."
As you see, one uses
to the other doesn't. That's why I thought they were equal. So there must be a kind of misinformation in the sentences.