At what height is a guy considered short?

For the record, I'm 5'8.5". I workout 5 days a week with 6 hours per day and I'm generally considered intelligent/friendly. However, I've been deemed short my whole life (Short bloodline so I can't help it) and as a result, my self confidence has been well into the negatives for most of my life. I purely want to know at what height does shortness begin.
At what height is a guy considered short?
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