Ok, here it goes:
His birthday is Jan 6, 1993 (making him 18 years old)
They start school later in Lithunaia than they do in America
This resulted in him being 1 year older than others in his grade, upon moving to America
At the end of his sophomore year (age 17) he decided to take on extra classes in order to skip his junior year and graduate the same age as everyone else in America
This now makes him a high school senior who just turned 18.
So he was both born in 1993 and skipped a year of high school, you f#cking moron.