It's not totally different Shalaby from how we learn it, but they have the advantage of growing up in an environment where people speak Chinese. So obviously their oral Chinese will be better. My guess is that for the rest it's exactly like us. A combination of pinyin and characters. (You do know that when Chinese people check a dictionary for a new character they look for the pronunciation in pinyin as well?)
For example I know one guy who can speak some Hakka but he can't write the characters. He just picked that up from his parents and grandparents. If they had spoken Mandarin he would've had an advantage over us.
Hehe, Cherry maybe we should opt for adoption and live with a Chinese family. That would really do wonders for our skills, hehe.