how did my dad avoid service in vietnam?

by peepeepoopoocacahead

My dad was born in 1951 and therefore would have been in the 1970 draft lottery. When I was young i recall him telling a story that his number was #110 and that he lucked out because they only went up to number 108 that year. I decided to look this up recently and found that his draft number was in fact #110, BUT I also learned that the draft went up to #125 that year. My father is dead now and im curious about how he avoided service.. Other than failing a physical or a secret history of fleeing to Canada, both of which I believe are unlikely, does any have any further information about how the draft worked and how my father may have avoided service? Thank you!

Tacoza