[BORN TO BE RICH] Among South Korea's richest aged 40 years or younger, LG chairman’s the adopted son Koo Gwang-mo, 38, of LG Group is the wealthiest. His net worth is estimated at 751.8 billion won (US$650.5 million).LG Corp. vice president Koo Gwang-mo.Koo is the great grandson of LG’s founder, the late Koo In-hoe. He was born to Heesung Group chairman Koo Bong-neung, but was adopted by his uncle Koo Bon-moo, chairman of LG. Gwang-mo is currently a vice president of LG Corp. He was promoted to