Windhorst already employs 100 people in a group spanning 13 companies dealing in everything from electronic components to office leasing and reaching from Germany to Hong Kong and China.
While his contemporaries were reading Walt Disney comics under the desk at secondary school, Windhorst was already devouring business magazines.
"I was always interested in linkages, strategies and industrial problems," Windhorst said in his small home town of Rahden near Osnabr--ck in northwestern Germany.
While the young entrepreneurs of yesteryear started out selling newspapers or washing cars, Windhorst found the 1990s way to make his first buck.
He bought electronic components cheaply in Asia and hawked them to retailers at home -- off the back of his moped. He had already left school at 16, finding that it was not teaching him much that he needed to know.
A year later, Windhorst is assembling his own line of personal computers to sell in one of the most competitive markets there is, and sounding for all the world like a seasoned company executive.
"I had to set up subsidiaries in London and Hong Kong and build up service and distribution companies in Germany and France," he said.
Like any good industrialist, Windhorst has diversified to spread his opportunities and risks.
Electronics -- a field he entered with the benefit of his father's experience in retailing personal computers -- is his main earner with annual turnover of some 50 million Deutsche marks ($32 million).
But the Windhorst Group also has a partnership with a Chinese firm to rent out office space in Hong Kong.
It imports precious metals and inorganic specialty chemicals from China, and sells machinery and manufacturing plants to East Asia.
And then there are another three or four major projects which are not quite ready to be publicized yet, group spokesman Frank Gorka says.
But there is more to Windhorst than just making money.
The young man, who also speaks Chinese, makes time to philosophize about business success and the difference between European and Asian approaches.
"I would like to combine Far Eastern ways of thinking with European-style strategy," he says.
"Just like in a personal computer, things have to network with each other -- Asian soul with European heart, German thoroughness with Far Eastern instinct," he says.
For the next few days around his 18th birthday, however, Windhorst will have a more mundane concern.
Not that he'll be annoying his parents by staying out all night partying -- Windhorst's graduation to adulthood means a corporate restructuring to take account of his new legal status.
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